Merge branch 'master' of https://github.com/MoonchildProductions/UXP into _testBranch_test_1

76 files changed, 1414 insertions, 1742 deletions

diff --git a/js/src/Makefile.in b/js/src/Makefile.in
index 3be6a6781..b007954b1 100644
--- a/js/src/Makefile.in
+++ b/js/src/Makefile.in
@@ -147,13 +147,6 @@ ifeq ($(OS_ARCH),AIX)
 CFLAGS		+= -qsuppress=1540-1281 -qsuppress=1540-1608
 CXXFLAGS	+= -qsuppress=1540-1281 -qsuppress=1540-1608
 endif
-ifeq ($(OS_ARCH),HP-UX)
-# Suppress warnings from aCC
-# 3055: anonymous unions declaring types
-# 4189: offsetof() on non-POD types
-CFLAGS		+= +W3055,4189
-CXXFLAGS	+= +W3055,4189
-endif
 endif
 ifeq ($(OS_ARCH),SunOS)
 ifeq ($(TARGET_CPU),sparc)
diff --git a/js/src/aclocal.m4 b/js/src/aclocal.m4
index 627837a41..abbbd4873 100644
--- a/js/src/aclocal.m4
+++ b/js/src/aclocal.m4
@@ -25,7 +25,6 @@ builtin(include, ../../build/autoconf/zlib.m4)dnl
 builtin(include, ../../build/autoconf/icu.m4)dnl
 builtin(include, ../../build/autoconf/clang-plugin.m4)dnl
 builtin(include, ../../build/autoconf/alloc.m4)dnl
-builtin(include, ../../build/autoconf/jemalloc.m4)dnl
 builtin(include, ../../build/autoconf/sanitize.m4)dnl
 builtin(include, ../../build/autoconf/ios.m4)dnl
 
diff --git a/js/src/builtin/Array.js b/js/src/builtin/Array.js
index 45f90a7b8..30e6fb35f 100644
--- a/js/src/builtin/Array.js
+++ b/js/src/builtin/Array.js
@@ -711,13 +711,14 @@ function CreateArrayIterator(obj, kind) {
 // http://www.ecma-international.org/ecma-262/6.0/index.html#sec-%arrayiteratorprototype%.next
 function ArrayIteratorNext() {
     // Step 1-3.
-    if (!IsObject(this) || !IsArrayIterator(this)) {
+    var obj;
+    if (!IsObject(this) || (obj = GuardToArrayIterator(this)) === null) {
         return callFunction(CallArrayIteratorMethodIfWrapped, this,
                             "ArrayIteratorNext");
     }
 
     // Step 4.
-    var a = UnsafeGetReservedSlot(this, ITERATOR_SLOT_TARGET);
+    var a = UnsafeGetReservedSlot(obj, ITERATOR_SLOT_TARGET);
     var result = { value: undefined, done: false };
 
     // Step 5.
@@ -728,10 +729,10 @@ function ArrayIteratorNext() {
 
     // Step 6.
     // The index might not be an integer, so we have to do a generic get here.
-    var index = UnsafeGetReservedSlot(this, ITERATOR_SLOT_NEXT_INDEX);
+    var index = UnsafeGetReservedSlot(obj, ITERATOR_SLOT_NEXT_INDEX);
 
     // Step 7.
-    var itemKind = UnsafeGetInt32FromReservedSlot(this, ITERATOR_SLOT_ITEM_KIND);
+    var itemKind = UnsafeGetInt32FromReservedSlot(obj, ITERATOR_SLOT_ITEM_KIND);
 
     // Step 8-9.
     var len = IsPossiblyWrappedTypedArray(a)
@@ -740,13 +741,13 @@ function ArrayIteratorNext() {
 
     // Step 10.
     if (index >= len) {
-        UnsafeSetReservedSlot(this, ITERATOR_SLOT_TARGET, null);
+        UnsafeSetReservedSlot(obj, ITERATOR_SLOT_TARGET, null);
         result.done = true;
         return result;
     }
 
     // Step 11.
-    UnsafeSetReservedSlot(this, ITERATOR_SLOT_NEXT_INDEX, index + 1);
+    UnsafeSetReservedSlot(obj, ITERATOR_SLOT_NEXT_INDEX, index + 1);
 
     // Step 16.
     if (itemKind === ITEM_KIND_VALUE) {
@@ -900,11 +901,7 @@ function ArrayToLocaleString(locales, options) {
     if (firstElement === undefined || firstElement === null) {
         R = "";
     } else {
-#if EXPOSE_INTL_API
         R = ToString(callContentFunction(firstElement.toLocaleString, firstElement, locales, options));
-#else
-        R = ToString(callContentFunction(firstElement.toLocaleString, firstElement));
-#endif
     }
 
     // Step 3 (reordered).
@@ -919,11 +916,7 @@ function ArrayToLocaleString(locales, options) {
         // Steps 9.a, 9.c-e.
         R += separator;
         if (!(nextElement === undefined || nextElement === null)) {
-#if EXPOSE_INTL_API
             R += ToString(callContentFunction(nextElement.toLocaleString, nextElement, locales, options));
-#else
-            R += ToString(callContentFunction(nextElement.toLocaleString, nextElement));
-#endif
         }
     }
 
diff --git a/js/src/builtin/Intl.cpp b/js/src/builtin/Intl.cpp
index 3a20c487b..71f7b58d4 100644
--- a/js/src/builtin/Intl.cpp
+++ b/js/src/builtin/Intl.cpp
@@ -23,7 +23,6 @@
 #include "jsobj.h"
 
 #include "builtin/IntlTimeZoneData.h"
-#if ENABLE_INTL_API
 #include "unicode/ucal.h"
 #include "unicode/ucol.h"
 #include "unicode/udat.h"
@@ -32,7 +31,6 @@
 #include "unicode/unum.h"
 #include "unicode/unumsys.h"
 #include "unicode/ustring.h"
-#endif
 #include "vm/DateTime.h"
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
@@ -60,512 +58,6 @@ using mozilla::PodCopy;
  * http://userguide.icu-project.org/design#TOC-Error-Handling
  */
 
-
-/******************** ICU stubs ********************/
-
-#if !ENABLE_INTL_API
-
-/*
- * When the Internationalization API isn't enabled, we also shouldn't link
- * against ICU. However, we still want to compile this code in order to prevent
- * bit rot. The following stub implementations for ICU functions make this
- * possible. The functions using them should never be called, so they assert
- * and return error codes. Signatures adapted from ICU header files locid.h,
- * numsys.h, ucal.h, ucol.h, udat.h, udatpg.h, uenum.h, unum.h; see the ICU
- * directory for license.
- */
-
-typedef bool UBool;
-typedef char16_t UChar;
-typedef double UDate;
-
-enum UErrorCode {
-    U_ZERO_ERROR,
-    U_BUFFER_OVERFLOW_ERROR,
-};
-
-static inline UBool
-U_FAILURE(UErrorCode code)
-{
-    MOZ_CRASH("U_FAILURE: Intl API disabled");
-}
-
-inline const UChar*
-Char16ToUChar(const char16_t* chars)
-{
-    MOZ_CRASH("Char16ToUChar: Intl API disabled");
-}
-
-inline UChar*
-Char16ToUChar(char16_t* chars)
-{
-    MOZ_CRASH("Char16ToUChar: Intl API disabled");
-}
-
-static int32_t
-u_strlen(const UChar* s)
-{
-    MOZ_CRASH("u_strlen: Intl API disabled");
-}
-
-struct UEnumeration;
-
-static int32_t
-uenum_count(UEnumeration* en, UErrorCode* status)
-{
-    MOZ_CRASH("uenum_count: Intl API disabled");
-}
-
-static const char*
-uenum_next(UEnumeration* en, int32_t* resultLength, UErrorCode* status)
-{
-    MOZ_CRASH("uenum_next: Intl API disabled");
-}
-
-static void
-uenum_close(UEnumeration* en)
-{
-    MOZ_CRASH("uenum_close: Intl API disabled");
-}
-
-struct UCollator;
-
-enum UColAttribute {
-    UCOL_ALTERNATE_HANDLING,
-    UCOL_CASE_FIRST,
-    UCOL_CASE_LEVEL,
-    UCOL_NORMALIZATION_MODE,
-    UCOL_STRENGTH,
-    UCOL_NUMERIC_COLLATION,
-};
-
-enum UColAttributeValue {
-    UCOL_DEFAULT = -1,
-    UCOL_PRIMARY = 0,
-    UCOL_SECONDARY = 1,
-    UCOL_TERTIARY = 2,
-    UCOL_OFF = 16,
-    UCOL_ON = 17,
-    UCOL_SHIFTED = 20,
-    UCOL_LOWER_FIRST = 24,
-    UCOL_UPPER_FIRST = 25,
-};
-
-enum UCollationResult {
-    UCOL_EQUAL = 0,
-    UCOL_GREATER = 1,
-    UCOL_LESS = -1
-};
-
-static int32_t
-ucol_countAvailable()
-{
-    MOZ_CRASH("ucol_countAvailable: Intl API disabled");
-}
-
-static const char*
-ucol_getAvailable(int32_t localeIndex)
-{
-    MOZ_CRASH("ucol_getAvailable: Intl API disabled");
-}
-
-static UCollator*
-ucol_open(const char* loc, UErrorCode* status)
-{
-    MOZ_CRASH("ucol_open: Intl API disabled");
-}
-
-static void
-ucol_setAttribute(UCollator* coll, UColAttribute attr, UColAttributeValue value, UErrorCode* status)
-{
-    MOZ_CRASH("ucol_setAttribute: Intl API disabled");
-}
-
-static UCollationResult
-ucol_strcoll(const UCollator* coll, const UChar* source, int32_t sourceLength,
-             const UChar* target, int32_t targetLength)
-{
-    MOZ_CRASH("ucol_strcoll: Intl API disabled");
-}
-
-static void
-ucol_close(UCollator* coll)
-{
-    MOZ_CRASH("ucol_close: Intl API disabled");
-}
-
-static UEnumeration*
-ucol_getKeywordValuesForLocale(const char* key, const char* locale, UBool commonlyUsed,
-                               UErrorCode* status)
-{
-    MOZ_CRASH("ucol_getKeywordValuesForLocale: Intl API disabled");
-}
-
-struct UParseError;
-struct UFieldPosition;
-struct UFieldPositionIterator;
-typedef void* UNumberFormat;
-
-enum UNumberFormatStyle {
-    UNUM_DECIMAL = 1,
-    UNUM_CURRENCY,
-    UNUM_PERCENT,
-    UNUM_CURRENCY_ISO,
-    UNUM_CURRENCY_PLURAL,
-};
-
-enum UNumberFormatRoundingMode {
-    UNUM_ROUND_HALFUP,
-};
-
-enum UNumberFormatAttribute {
-    UNUM_GROUPING_USED,
-    UNUM_MIN_INTEGER_DIGITS,
-    UNUM_MAX_FRACTION_DIGITS,
-    UNUM_MIN_FRACTION_DIGITS,
-    UNUM_ROUNDING_MODE,
-    UNUM_SIGNIFICANT_DIGITS_USED,
-    UNUM_MIN_SIGNIFICANT_DIGITS,
-    UNUM_MAX_SIGNIFICANT_DIGITS,
-};
-
-enum UNumberFormatTextAttribute {
-    UNUM_CURRENCY_CODE,
-};
-
-static int32_t
-unum_countAvailable()
-{
-    MOZ_CRASH("unum_countAvailable: Intl API disabled");
-}
-
-static const char*
-unum_getAvailable(int32_t localeIndex)
-{
-    MOZ_CRASH("unum_getAvailable: Intl API disabled");
-}
-
-static UNumberFormat*
-unum_open(UNumberFormatStyle style, const UChar* pattern, int32_t patternLength,
-          const char* locale, UParseError* parseErr, UErrorCode* status)
-{
-    MOZ_CRASH("unum_open: Intl API disabled");
-}
-
-static void
-unum_setAttribute(UNumberFormat* fmt, UNumberFormatAttribute  attr, int32_t newValue)
-{
-    MOZ_CRASH("unum_setAttribute: Intl API disabled");
-}
-
-static int32_t
-unum_formatDouble(const UNumberFormat* fmt, double number, UChar* result,
-                  int32_t resultLength, UFieldPosition* pos, UErrorCode* status)
-{
-    MOZ_CRASH("unum_formatDouble: Intl API disabled");
-}
-
-static void
-unum_close(UNumberFormat* fmt)
-{
-    MOZ_CRASH("unum_close: Intl API disabled");
-}
-
-static void
-unum_setTextAttribute(UNumberFormat* fmt, UNumberFormatTextAttribute tag, const UChar* newValue,
-                      int32_t newValueLength, UErrorCode* status)
-{
-    MOZ_CRASH("unum_setTextAttribute: Intl API disabled");
-}
-
-typedef void* UNumberingSystem;
-
-static UNumberingSystem*
-unumsys_open(const char* locale, UErrorCode* status)
-{
-    MOZ_CRASH("unumsys_open: Intl API disabled");
-}
-
-static const char*
-unumsys_getName(const UNumberingSystem* unumsys)
-{
-    MOZ_CRASH("unumsys_getName: Intl API disabled");
-}
-
-static void
-unumsys_close(UNumberingSystem* unumsys)
-{
-    MOZ_CRASH("unumsys_close: Intl API disabled");
-}
-
-typedef void* UCalendar;
-
-enum UCalendarType {
-    UCAL_TRADITIONAL,
-    UCAL_DEFAULT = UCAL_TRADITIONAL,
-    UCAL_GREGORIAN
-};
-
-enum UCalendarAttribute {
-    UCAL_FIRST_DAY_OF_WEEK,
-    UCAL_MINIMAL_DAYS_IN_FIRST_WEEK
-};
-
-enum UCalendarDaysOfWeek {
-    UCAL_SUNDAY,
-    UCAL_MONDAY,
-    UCAL_TUESDAY,
-    UCAL_WEDNESDAY,
-    UCAL_THURSDAY,
-    UCAL_FRIDAY,
-    UCAL_SATURDAY
-};
-
-enum UCalendarWeekdayType {
-    UCAL_WEEKDAY,
-    UCAL_WEEKEND,
-    UCAL_WEEKEND_ONSET,
-    UCAL_WEEKEND_CEASE
-};
-
-enum UCalendarDateFields {
-    UCAL_ERA,
-    UCAL_YEAR,
-    UCAL_MONTH,
-    UCAL_WEEK_OF_YEAR,
-    UCAL_WEEK_OF_MONTH,
-    UCAL_DATE,
-    UCAL_DAY_OF_YEAR,
-    UCAL_DAY_OF_WEEK,
-    UCAL_DAY_OF_WEEK_IN_MONTH,
-    UCAL_AM_PM,
-    UCAL_HOUR,
-    UCAL_HOUR_OF_DAY,
-    UCAL_MINUTE,
-    UCAL_SECOND,
-    UCAL_MILLISECOND,
-    UCAL_ZONE_OFFSET,
-    UCAL_DST_OFFSET,
-    UCAL_YEAR_WOY,
-    UCAL_DOW_LOCAL,
-    UCAL_EXTENDED_YEAR,
-    UCAL_JULIAN_DAY,
-    UCAL_MILLISECONDS_IN_DAY,
-    UCAL_IS_LEAP_MONTH,
-    UCAL_FIELD_COUNT,
-    UCAL_DAY_OF_MONTH = UCAL_DATE
-};
-
-static UCalendar*
-ucal_open(const UChar* zoneID, int32_t len, const char* locale,
-          UCalendarType type, UErrorCode* status)
-{
-    MOZ_CRASH("ucal_open: Intl API disabled");
-}
-
-static const char*
-ucal_getType(const UCalendar* cal, UErrorCode* status)
-{
-    MOZ_CRASH("ucal_getType: Intl API disabled");
-}
-
-static UEnumeration*
-ucal_getKeywordValuesForLocale(const char* key, const char* locale,
-                               UBool commonlyUsed, UErrorCode* status)
-{
-    MOZ_CRASH("ucal_getKeywordValuesForLocale: Intl API disabled");
-}
-
-static void
-ucal_close(UCalendar* cal)
-{
-    MOZ_CRASH("ucal_close: Intl API disabled");
-}
-
-static UCalendarWeekdayType
-ucal_getDayOfWeekType(const UCalendar *cal, UCalendarDaysOfWeek dayOfWeek, UErrorCode* status)
-{
-    MOZ_CRASH("ucal_getDayOfWeekType: Intl API disabled");
-}
-
-static int32_t
-ucal_getAttribute(const UCalendar*    cal,
-                  UCalendarAttribute  attr)
-{
-    MOZ_CRASH("ucal_getAttribute: Intl API disabled");
-}
-
-static int32_t
-ucal_get(const UCalendar *cal, UCalendarDateFields field, UErrorCode *status)
-{
-    MOZ_CRASH("ucal_get: Intl API disabled");
-}
-
-static UEnumeration*
-ucal_openTimeZones(UErrorCode* status)
-{
-    MOZ_CRASH("ucal_openTimeZones: Intl API disabled");
-}
-
-static int32_t
-ucal_getCanonicalTimeZoneID(const UChar* id, int32_t len, UChar* result, int32_t resultCapacity,
-                            UBool* isSystemID, UErrorCode* status)
-{
-    MOZ_CRASH("ucal_getCanonicalTimeZoneID: Intl API disabled");
-}
-
-static int32_t
-ucal_getDefaultTimeZone(UChar* result, int32_t resultCapacity, UErrorCode* status)
-{
-    MOZ_CRASH("ucal_getDefaultTimeZone: Intl API disabled");
-}
-
-typedef void* UDateTimePatternGenerator;
-
-static UDateTimePatternGenerator*
-udatpg_open(const char* locale, UErrorCode* pErrorCode)
-{
-    MOZ_CRASH("udatpg_open: Intl API disabled");
-}
-
-static int32_t
-udatpg_getBestPattern(UDateTimePatternGenerator* dtpg, const UChar* skeleton,
-                      int32_t length, UChar* bestPattern, int32_t capacity,
-                      UErrorCode* pErrorCode)
-{
-    MOZ_CRASH("udatpg_getBestPattern: Intl API disabled");
-}
-
-static void
-udatpg_close(UDateTimePatternGenerator* dtpg)
-{
-    MOZ_CRASH("udatpg_close: Intl API disabled");
-}
-
-typedef void* UCalendar;
-typedef void* UDateFormat;
-
-enum UDateFormatField {
-    UDAT_ERA_FIELD = 0,
-    UDAT_YEAR_FIELD = 1,
-    UDAT_MONTH_FIELD = 2,
-    UDAT_DATE_FIELD = 3,
-    UDAT_HOUR_OF_DAY1_FIELD = 4,
-    UDAT_HOUR_OF_DAY0_FIELD = 5,
-    UDAT_MINUTE_FIELD = 6,
-    UDAT_SECOND_FIELD = 7,
-    UDAT_FRACTIONAL_SECOND_FIELD = 8,
-    UDAT_DAY_OF_WEEK_FIELD = 9,
-    UDAT_DAY_OF_YEAR_FIELD = 10,
-    UDAT_DAY_OF_WEEK_IN_MONTH_FIELD = 11,
-    UDAT_WEEK_OF_YEAR_FIELD = 12,
-    UDAT_WEEK_OF_MONTH_FIELD = 13,
-    UDAT_AM_PM_FIELD = 14,
-    UDAT_HOUR1_FIELD = 15,
-    UDAT_HOUR0_FIELD = 16,
-    UDAT_TIMEZONE_FIELD = 17,
-    UDAT_YEAR_WOY_FIELD = 18,
-    UDAT_DOW_LOCAL_FIELD = 19,
-    UDAT_EXTENDED_YEAR_FIELD = 20,
-    UDAT_JULIAN_DAY_FIELD = 21,
-    UDAT_MILLISECONDS_IN_DAY_FIELD = 22,
-    UDAT_TIMEZONE_RFC_FIELD = 23,
-    UDAT_TIMEZONE_GENERIC_FIELD = 24,
-    UDAT_STANDALONE_DAY_FIELD = 25,
-    UDAT_STANDALONE_MONTH_FIELD = 26,
-    UDAT_QUARTER_FIELD = 27,
-    UDAT_STANDALONE_QUARTER_FIELD = 28,
-    UDAT_TIMEZONE_SPECIAL_FIELD = 29,
-    UDAT_YEAR_NAME_FIELD = 30,
-    UDAT_TIMEZONE_LOCALIZED_GMT_OFFSET_FIELD = 31,
-    UDAT_TIMEZONE_ISO_FIELD = 32,
-    UDAT_TIMEZONE_ISO_LOCAL_FIELD = 33,
-    UDAT_RELATED_YEAR_FIELD = 34,
-    UDAT_AM_PM_MIDNIGHT_NOON_FIELD = 35,
-    UDAT_FLEXIBLE_DAY_PERIOD_FIELD = 36,
-    UDAT_TIME_SEPARATOR_FIELD = 37,
-    UDAT_FIELD_COUNT = 38
-};
-
-enum UDateFormatStyle {
-    UDAT_PATTERN = -2,
-    UDAT_IGNORE = UDAT_PATTERN
-};
-
-static int32_t
-udat_countAvailable()
-{
-    MOZ_CRASH("udat_countAvailable: Intl API disabled");
-}
-
-static const char*
-udat_getAvailable(int32_t localeIndex)
-{
-    MOZ_CRASH("udat_getAvailable: Intl API disabled");
-}
-
-static UDateFormat*
-udat_open(UDateFormatStyle timeStyle, UDateFormatStyle dateStyle, const char* locale,
-          const UChar* tzID, int32_t tzIDLength, const UChar* pattern,
-          int32_t patternLength, UErrorCode* status)
-{
-    MOZ_CRASH("udat_open: Intl API disabled");
-}
-
-static const UCalendar*
-udat_getCalendar(const UDateFormat* fmt)
-{
-    MOZ_CRASH("udat_getCalendar: Intl API disabled");
-}
-
-static void
-ucal_setGregorianChange(UCalendar* cal, UDate date, UErrorCode* pErrorCode)
-{
-    MOZ_CRASH("ucal_setGregorianChange: Intl API disabled");
-}
-
-static int32_t
-udat_format(const UDateFormat* format, UDate dateToFormat, UChar* result,
-            int32_t resultLength, UFieldPosition* position, UErrorCode* status)
-{
-    MOZ_CRASH("udat_format: Intl API disabled");
-}
-
-static int32_t
-udat_formatForFields(const UDateFormat* format, UDate dateToFormat,
-                     UChar* result, int32_t resultLength, UFieldPositionIterator* fpositer,
-                     UErrorCode* status)
-{
-    MOZ_CRASH("udat_formatForFields: Intl API disabled");
-}
-
-static UFieldPositionIterator*
-ufieldpositer_open(UErrorCode* status)
-{
-    MOZ_CRASH("ufieldpositer_open: Intl API disabled");
-}
-
-static void
-ufieldpositer_close(UFieldPositionIterator* fpositer)
-{
-    MOZ_CRASH("ufieldpositer_close: Intl API disabled");
-}
-
-static int32_t
-ufieldpositer_next(UFieldPositionIterator* fpositer, int32_t* beginIndex, int32_t* endIndex)
-{
-    MOZ_CRASH("ufieldpositer_next: Intl API disabled");
-}
-
-static void
-udat_close(UDateFormat* format)
-{
-    MOZ_CRASH("udat_close: Intl API disabled");
-}
-
-#endif
-
-
 /******************** Common to Intl constructors ********************/
 
 static bool
@@ -615,7 +107,6 @@ intl_availableLocales(JSContext* cx, CountAvailable countAvailable,
     if (!locales)
         return false;
 
-#if ENABLE_INTL_API
     uint32_t count = countAvailable();
     RootedValue t(cx, BooleanValue(true));
     for (uint32_t i = 0; i < count; i++) {
@@ -635,7 +126,7 @@ intl_availableLocales(JSContext* cx, CountAvailable countAvailable,
             return false;
         }
     }
-#endif
+
     result.setObject(*locales);
     return true;
 }
@@ -2921,6 +2412,296 @@ js::intl_GetCalendarInfo(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
+template<size_t N>
+inline bool
+MatchPart(const char** pattern, const char (&part)[N])
+{
+    if (strncmp(*pattern, part, N - 1))
+        return false;
+
+    *pattern += N - 1;
+    return true;
+}
+
+bool
+js::intl_ComputeDisplayNames(JSContext* cx, unsigned argc, Value* vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    MOZ_ASSERT(args.length() == 3);
+    // 1. Assert: locale is a string.
+    MOZ_ASSERT(args[0].isString());
+    // 2. Assert: style is a string.
+    MOZ_ASSERT(args[1].isString());
+    // 3. Assert: keys is an Array.
+    MOZ_ASSERT(args[2].isObject());
+
+    JSAutoByteString locale(cx, args[0].toString());
+    if (!locale)
+        return false;
+
+    JSAutoByteString style(cx, args[1].toString());
+    if (!style)
+        return false;
+
+    RootedArrayObject keys(cx, &args[2].toObject().as<ArrayObject>());
+    if (!keys)
+        return false;
+
+    // 4. Let result be ArrayCreate(0).
+    RootedArrayObject result(cx, NewDenseUnallocatedArray(cx, keys->length()));
+    if (!result)
+        return false;
+
+    UErrorCode status = U_ZERO_ERROR;
+
+    UDateFormat* fmt =
+        udat_open(UDAT_DEFAULT, UDAT_DEFAULT, icuLocale(locale.ptr()),
+        nullptr, 0, nullptr, 0, &status);
+    if (U_FAILURE(status)) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_INTERNAL_INTL_ERROR);
+        return false;
+    }
+    ScopedICUObject<UDateFormat, udat_close> datToClose(fmt);
+
+    // UDateTimePatternGenerator will be needed for translations of date and
+    // time fields like "month", "week", "day" etc.
+    UDateTimePatternGenerator* dtpg = udatpg_open(icuLocale(locale.ptr()), &status);
+    if (U_FAILURE(status)) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_INTERNAL_INTL_ERROR);
+        return false;
+    }
+    ScopedICUObject<UDateTimePatternGenerator, udatpg_close> datPgToClose(dtpg);
+
+    RootedValue keyValue(cx);
+    RootedString keyValStr(cx);
+    RootedValue wordVal(cx);
+    Vector<char16_t, INITIAL_CHAR_BUFFER_SIZE> chars(cx);
+    if (!chars.resize(INITIAL_CHAR_BUFFER_SIZE))
+        return false;
+
+    // 5. For each element of keys,
+    for (uint32_t i = 0; i < keys->length(); i++) {
+        /**
+         * We iterate over keys array looking for paths that we have code
+         * branches for.
+         *
+         * For any unknown path branch, the wordVal will keep NullValue and
+         * we'll throw at the end.
+         */
+
+        if (!GetElement(cx, keys, keys, i, &keyValue))
+            return false;
+
+        JSAutoByteString pattern;
+        keyValStr = keyValue.toString();
+        if (!pattern.encodeUtf8(cx, keyValStr))
+            return false;
+
+        wordVal.setNull();
+
+        // 5.a. Perform an implementation dependent algorithm to map a key to a
+        //      corresponding display name.
+        const char* pat = pattern.ptr();
+
+        if (!MatchPart(&pat, "dates")) {
+            JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+            return false;
+        }
+
+        if (!MatchPart(&pat, "/")) {
+            JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+            return false;
+        }
+
+        if (MatchPart(&pat, "fields")) {
+            if (!MatchPart(&pat, "/")) {
+                JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                return false;
+            }
+
+            UDateTimePatternField fieldType;
+
+            if (MatchPart(&pat, "year")) {
+                fieldType = UDATPG_YEAR_FIELD;
+            } else if (MatchPart(&pat, "month")) {
+                fieldType = UDATPG_MONTH_FIELD;
+            } else if (MatchPart(&pat, "week")) {
+                fieldType = UDATPG_WEEK_OF_YEAR_FIELD;
+            } else if (MatchPart(&pat, "day")) {
+                fieldType = UDATPG_DAY_FIELD;
+            } else {
+                JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                return false;
+            }
+
+            // This part must be the final part with no trailing data.
+            if (*pat != '\0') {
+                JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                return false;
+            }
+
+            int32_t resultSize;
+
+            const UChar* value = udatpg_getAppendItemName(dtpg, fieldType, &resultSize);
+            if (U_FAILURE(status)) {
+                JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_INTERNAL_INTL_ERROR);
+                return false;
+            }
+
+            JSString* word = NewStringCopyN<CanGC>(cx, UCharToChar16(value), resultSize);
+            if (!word)
+                return false;
+
+            wordVal.setString(word);
+        } else if (MatchPart(&pat, "gregorian")) {
+            if (!MatchPart(&pat, "/")) {
+                JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                return false;
+            }
+
+            UDateFormatSymbolType symbolType;
+            int32_t index;
+
+            if (MatchPart(&pat, "months")) {
+                if (!MatchPart(&pat, "/")) {
+                    JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                    return false;
+                }
+
+                if (equal(style, "narrow")) {
+                    symbolType = UDAT_STANDALONE_NARROW_MONTHS;
+                } else if (equal(style, "short")) {
+                    symbolType = UDAT_STANDALONE_SHORT_MONTHS;
+                } else {
+                    MOZ_ASSERT(equal(style, "long"));
+                    symbolType = UDAT_STANDALONE_MONTHS;
+                }
+
+                if (MatchPart(&pat, "january")) {
+                    index = UCAL_JANUARY;
+                } else if (MatchPart(&pat, "february")) {
+                    index = UCAL_FEBRUARY;
+                } else if (MatchPart(&pat, "march")) {
+                    index = UCAL_MARCH;
+                } else if (MatchPart(&pat, "april")) {
+                    index = UCAL_APRIL;
+                } else if (MatchPart(&pat, "may")) {
+                    index = UCAL_MAY;
+                } else if (MatchPart(&pat, "june")) {
+                    index = UCAL_JUNE;
+                } else if (MatchPart(&pat, "july")) {
+                    index = UCAL_JULY;
+                } else if (MatchPart(&pat, "august")) {
+                    index = UCAL_AUGUST;
+                } else if (MatchPart(&pat, "september")) {
+                    index = UCAL_SEPTEMBER;
+                } else if (MatchPart(&pat, "october")) {
+                    index = UCAL_OCTOBER;
+                } else if (MatchPart(&pat, "november")) {
+                    index = UCAL_NOVEMBER;
+                } else if (MatchPart(&pat, "december")) {
+                    index = UCAL_DECEMBER;
+                } else {
+                    JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                    return false;
+                }
+            } else if (MatchPart(&pat, "weekdays")) {
+                if (!MatchPart(&pat, "/")) {
+                    JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                    return false;
+                }
+
+                if (equal(style, "narrow")) {
+                    symbolType = UDAT_STANDALONE_NARROW_WEEKDAYS;
+                } else if (equal(style, "short")) {
+                    symbolType = UDAT_STANDALONE_SHORT_WEEKDAYS;
+                } else {
+                    MOZ_ASSERT(equal(style, "long"));
+                    symbolType = UDAT_STANDALONE_WEEKDAYS;
+                }
+
+                if (MatchPart(&pat, "monday")) {
+                    index = UCAL_MONDAY;
+                } else if (MatchPart(&pat, "tuesday")) {
+                    index = UCAL_TUESDAY;
+                } else if (MatchPart(&pat, "wednesday")) {
+                    index = UCAL_WEDNESDAY;
+                } else if (MatchPart(&pat, "thursday")) {
+                    index = UCAL_THURSDAY;
+                } else if (MatchPart(&pat, "friday")) {
+                    index = UCAL_FRIDAY;
+                } else if (MatchPart(&pat, "saturday")) {
+                    index = UCAL_SATURDAY;
+                } else if (MatchPart(&pat, "sunday")) {
+                    index = UCAL_SUNDAY;
+                } else {
+                    JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                    return false;
+                }
+            } else if (MatchPart(&pat, "dayperiods")) {
+                if (!MatchPart(&pat, "/")) {
+                    JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                    return false;
+                }
+
+                symbolType = UDAT_AM_PMS;
+
+                if (MatchPart(&pat, "am")) {
+                    index = UCAL_AM;
+                } else if (MatchPart(&pat, "pm")) {
+                    index = UCAL_PM;
+                } else {
+                    JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                    return false;
+                }
+            } else {
+                JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                return false;
+            }
+
+            // This part must be the final part with no trailing data.
+            if (*pat != '\0') {
+                JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+                return false;
+            }
+
+            int32_t resultSize =
+                udat_getSymbols(fmt, symbolType, index, Char16ToUChar(chars.begin()),
+                                INITIAL_CHAR_BUFFER_SIZE, &status);
+            if (status == U_BUFFER_OVERFLOW_ERROR) {
+                if (!chars.resize(resultSize))
+                    return false;
+                status = U_ZERO_ERROR;
+                udat_getSymbols(fmt, symbolType, index, Char16ToUChar(chars.begin()),
+                                resultSize, &status);
+            }
+            if (U_FAILURE(status)) {
+                JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_INTERNAL_INTL_ERROR);
+                return false;
+            }
+
+            JSString* word = NewStringCopyN<CanGC>(cx, chars.begin(), resultSize);
+            if (!word)
+                return false;
+
+            wordVal.setString(word);
+        } else {
+            JS_ReportErrorNumberUTF8(cx, GetErrorMessage, nullptr, JSMSG_INVALID_KEY, pattern.ptr());
+            return false;
+        }
+
+        MOZ_ASSERT(wordVal.isString());
+
+        // 5.b. Append the result string to result.
+        if (!DefineElement(cx, result, i, wordVal))
+            return false;
+    }
+
+    // 6. Return result.
+    args.rval().setObject(*result);
+    return true;
+}
+
 /******************** Intl ********************/
 
 const Class js::IntlClass = {
diff --git a/js/src/builtin/Intl.h b/js/src/builtin/Intl.h
index 54764605b..9a1e44913 100644
--- a/js/src/builtin/Intl.h
+++ b/js/src/builtin/Intl.h
@@ -16,9 +16,7 @@
 #include "js/GCAPI.h"
 #include "js/GCHashTable.h"
 
-#if ENABLE_INTL_API
 #include "unicode/utypes.h"
-#endif
 
 /*
  * The Intl module specified by standard ECMA-402,
@@ -387,7 +385,48 @@ intl_FormatDateTime(JSContext* cx, unsigned argc, Value* vp);
 extern MOZ_MUST_USE bool
 intl_GetCalendarInfo(JSContext* cx, unsigned argc, Value* vp);
 
-#if ENABLE_INTL_API
+/**
+ * Returns an Array with CLDR-based fields display names.
+ * The function takes three arguments:
+ *
+ *   locale
+ *     BCP47 compliant locale string
+ *   style
+ *     A string with values: long or short or narrow
+ *   keys
+ *     An array or path-like strings that identify keys to be returned
+ *     At the moment the following types of keys are supported:
+ *
+ *       'dates/fields/{year|month|week|day}'
+ *       'dates/gregorian/months/{january|...|december}'
+ *       'dates/gregorian/weekdays/{sunday|...|saturday}'
+ *       'dates/gregorian/dayperiods/{am|pm}'
+ *
+ * Example:
+ *
+ * let info = intl_ComputeDisplayNames(
+ *   'en-US',
+ *   'long',
+ *   [
+ *     'dates/fields/year',
+ *     'dates/gregorian/months/january',
+ *     'dates/gregorian/weekdays/monday',
+ *     'dates/gregorian/dayperiods/am',
+ *   ]
+ * );
+ *
+ * Returned value:
+ *
+ * [
+ *   'year',
+ *   'January',
+ *   'Monday',
+ *   'AM'
+ * ]
+ */
+extern MOZ_MUST_USE bool
+intl_ComputeDisplayNames(JSContext* cx, unsigned argc, Value* vp);
+
 /**
  * Cast char16_t* strings to UChar* strings used by ICU.
  */
@@ -402,7 +441,18 @@ Char16ToUChar(char16_t* chars)
 {
   return reinterpret_cast<UChar*>(chars);
 }
-#endif // ENABLE_INTL_API
+
+inline char16_t*
+UCharToChar16(UChar* chars)
+{
+  return reinterpret_cast<char16_t*>(chars);
+}
+
+inline const char16_t*
+UCharToChar16(const UChar* chars)
+{
+  return reinterpret_cast<const char16_t*>(chars);
+}
 
 } // namespace js
 
diff --git a/js/src/builtin/Intl.js b/js/src/builtin/Intl.js
index 37c87365b..6391c3e70 100644
--- a/js/src/builtin/Intl.js
+++ b/js/src/builtin/Intl.js
@@ -21,9 +21,6 @@
          intl_availableCalendars: false,
          intl_patternForSkeleton: false,
          intl_FormatDateTime: false,
-         intl_SelectPluralRule: false,
-         intl_GetPluralCategories: false,
-         intl_GetCalendarInfo: false,
 */
 
 /*
@@ -860,7 +857,6 @@ function BestAvailableLocaleIgnoringDefault(availableLocales, locale) {
     return BestAvailableLocaleHelper(availableLocales, locale, false);
 }
 
-var noRelevantExtensionKeys = [];
 
 /**
  * Compares a BCP 47 language priority list against the set of locales in
@@ -1188,10 +1184,9 @@ function GetOption(options, property, type, values, fallback) {
  * Spec: ECMAScript Internationalization API Specification, 9.2.10.
  */
 function GetNumberOption(options, property, minimum, maximum, fallback) {
-    assert(typeof minimum === "number" && (minimum | 0) === minimum, "GetNumberOption");
-    assert(typeof maximum === "number" && (maximum | 0) === maximum, "GetNumberOption");
-    assert(typeof fallback === "number" && (fallback | 0) === fallback, "GetNumberOption");
-    assert(minimum <= fallback && fallback <= maximum, "GetNumberOption");
+    assert(typeof minimum === "number", "GetNumberOption");
+    assert(typeof maximum === "number", "GetNumberOption");
+    assert(fallback === undefined || (fallback >= minimum && fallback <= maximum), "GetNumberOption");
 
     // Step 1.
     var value = options[property];
@@ -1201,10 +1196,7 @@ function GetNumberOption(options, property, minimum, maximum, fallback) {
         value = ToNumber(value);
         if (Number_isNaN(value) || value < minimum || value > maximum)
             ThrowRangeError(JSMSG_INVALID_DIGITS_VALUE, value);
-
-        // Apply bitwise-or to convert -0 to +0 per ES2017, 5.2 and to ensure
-        // the result is an int32 value.
-        return std_Math_floor(value) | 0;
+        return std_Math_floor(value);
     }
 
     // Step 3.
@@ -1278,9 +1270,7 @@ function initializeIntlObject(obj) {
 function setLazyData(internals, type, lazyData)
 {
     assert(internals.type === "partial", "can't set lazy data for anything but a newborn");
-    assert(type === "Collator" || type === "DateTimeFormat" ||
-           type == "NumberFormat" || type === "PluralRules",
-           "bad type");
+    assert(type === "Collator" || type === "DateTimeFormat" || type == "NumberFormat", "bad type");
     assert(IsObject(lazyData), "non-object lazy data");
 
     // Set in reverse order so that the .type change is a barrier.
@@ -1330,9 +1320,7 @@ function isInitializedIntlObject(obj) {
     if (IsObject(internals)) {
         assert(callFunction(std_Object_hasOwnProperty, internals, "type"), "missing type");
         var type = internals.type;
-        assert(type === "partial" || type === "Collator" ||
-               type === "DateTimeFormat" || type === "NumberFormat" || type === "PluralRules",
-               "unexpected type");
+        assert(type === "partial" || type === "Collator" || type === "DateTimeFormat" || type === "NumberFormat", "unexpected type");
         assert(callFunction(std_Object_hasOwnProperty, internals, "lazyData"), "missing lazyData");
         assert(callFunction(std_Object_hasOwnProperty, internals, "internalProps"), "missing internalProps");
     } else {
@@ -1389,8 +1377,6 @@ function getInternals(obj)
         internalProps = resolveCollatorInternals(lazyData)
     else if (type === "DateTimeFormat")
         internalProps = resolveDateTimeFormatInternals(lazyData)
-    else if (type === "PluralRules")
-        internalProps = resolvePluralRulesInternals(lazyData)
     else
         internalProps = resolveNumberFormatInternals(lazyData);
     setInternalProperties(internals, internalProps);
@@ -1722,7 +1708,6 @@ function Intl_Collator_compare_get() {
     // Step 2.
     return internals.boundCompare;
 }
-_SetCanonicalName(Intl_Collator_compare_get, "get compare");
 
 
 /**
@@ -1791,37 +1776,45 @@ function resolveNumberFormatInternals(lazyNumberFormatData) {
     // Step 6.
     var opt = lazyNumberFormatData.opt;
 
+    // Compute effective locale.
+    // Step 9.
     var NumberFormat = numberFormatInternalProperties;
 
-    // Step 9.
+    // Step 10.
     var localeData = NumberFormat.localeData;
 
-    // Step 10.
+    // Step 11.
     var r = ResolveLocale(callFunction(NumberFormat.availableLocales, NumberFormat),
                           lazyNumberFormatData.requestedLocales,
                           lazyNumberFormatData.opt,
                           NumberFormat.relevantExtensionKeys,
                           localeData);
 
-    // Steps 11-12.  (Step 13 is not relevant to our implementation.)
+    // Steps 12-13.  (Step 14 is not relevant to our implementation.)
     internalProps.locale = r.locale;
     internalProps.numberingSystem = r.nu;
 
     // Compute formatting options.
-    // Step 15.
-    var style = lazyNumberFormatData.style;
-    internalProps.style = style;
+    // Step 16.
+    var s = lazyNumberFormatData.style;
+    internalProps.style = s;
 
-    // Steps 19, 21.
-    if (style === "currency") {
+    // Steps 20, 22.
+    if (s === "currency") {
         internalProps.currency = lazyNumberFormatData.currency;
         internalProps.currencyDisplay = lazyNumberFormatData.currencyDisplay;
     }
 
+    // Step 24.
     internalProps.minimumIntegerDigits = lazyNumberFormatData.minimumIntegerDigits;
+
+    // Steps 27.
     internalProps.minimumFractionDigits = lazyNumberFormatData.minimumFractionDigits;
+
+    // Step 30.
     internalProps.maximumFractionDigits = lazyNumberFormatData.maximumFractionDigits;
 
+    // Step 33.
     if ("minimumSignificantDigits" in lazyNumberFormatData) {
         // Note: Intl.NumberFormat.prototype.resolvedOptions() exposes the
         // actual presence (versus undefined-ness) of these properties.
@@ -1830,10 +1823,10 @@ function resolveNumberFormatInternals(lazyNumberFormatData) {
         internalProps.maximumSignificantDigits = lazyNumberFormatData.maximumSignificantDigits;
     }
 
-    // Step 27.
+    // Step 35.
     internalProps.useGrouping = lazyNumberFormatData.useGrouping;
 
-    // Step 34.
+    // Step 42.
     internalProps.boundFormat = undefined;
 
     // The caller is responsible for associating |internalProps| with the right
@@ -1861,44 +1854,6 @@ function getNumberFormatInternals(obj, methodName) {
     return internalProps;
 }
 
-/**
- * Applies digit options used for number formatting onto the intl object.
- *
- * Spec: ECMAScript Internationalization API Specification, 11.1.1.
- */
-function SetNumberFormatDigitOptions(lazyData, options, mnfdDefault, mxfdDefault) {
-    // We skip Step 1 because we set the properties on a lazyData object.
-
-    // Step 2-3.
-    assert(IsObject(options), "SetNumberFormatDigitOptions");
-    assert(typeof mnfdDefault === "number", "SetNumberFormatDigitOptions");
-    assert(typeof mxfdDefault === "number", "SetNumberFormatDigitOptions");
-    assert(mnfdDefault <= mxfdDefault, "SetNumberFormatDigitOptions");
-
-    // Steps 4-6.
-    const mnid = GetNumberOption(options, "minimumIntegerDigits", 1, 21, 1);
-    const mnfd = GetNumberOption(options, "minimumFractionDigits", 0, 20, mnfdDefault);
-    const mxfdActualDefault = std_Math_max(mnfd, mxfdDefault);
-    const mxfd = GetNumberOption(options, "maximumFractionDigits", mnfd, 20, mxfdActualDefault);
-
-    // Steps 7-8.
-    let mnsd = options.minimumSignificantDigits;
-    let mxsd = options.maximumSignificantDigits;
-
-    // Steps 9-11.
-    lazyData.minimumIntegerDigits = mnid;
-    lazyData.minimumFractionDigits = mnfd;
-    lazyData.maximumFractionDigits = mxfd;
-
-    // Step 12.
-    if (mnsd !== undefined || mxsd !== undefined) {
-        mnsd = GetNumberOption(options, "minimumSignificantDigits", 1, 21, 1);
-        mxsd = GetNumberOption(options, "maximumSignificantDigits", mnsd, 21, 21);
-        lazyData.minimumSignificantDigits = mnsd;
-        lazyData.maximumSignificantDigits = mxsd;
-    }
-}
-
 
 /**
  * Initializes an object as a NumberFormat.
@@ -1948,7 +1903,7 @@ function InitializeNumberFormat(numberFormat, locales, options) {
     //   }
     //
     // Note that lazy data is only installed as a final step of initialization,
-    // so every NumberFormat lazy data object has *all* these properties, never a
+    // so every Collator lazy data object has *all* these properties, never a
     // subset of them.
     var lazyNumberFormatData = std_Object_create(null);
 
@@ -1978,46 +1933,67 @@ function InitializeNumberFormat(numberFormat, locales, options) {
     opt.localeMatcher = matcher;
 
     // Compute formatting options.
-    // Step 14.
-    var style = GetOption(options, "style", "string", ["decimal", "percent", "currency"], "decimal");
-    lazyNumberFormatData.style = style;
+    // Step 15.
+    var s = GetOption(options, "style", "string", ["decimal", "percent", "currency"], "decimal");
+    lazyNumberFormatData.style = s;
 
-    // Steps 16-19.
+    // Steps 17-20.
     var c = GetOption(options, "currency", "string", undefined, undefined);
     if (c !== undefined && !IsWellFormedCurrencyCode(c))
         ThrowRangeError(JSMSG_INVALID_CURRENCY_CODE, c);
     var cDigits;
-    if (style === "currency") {
+    if (s === "currency") {
         if (c === undefined)
             ThrowTypeError(JSMSG_UNDEFINED_CURRENCY);
 
-        // Steps 19.a-c.
+        // Steps 20.a-c.
         c = toASCIIUpperCase(c);
         lazyNumberFormatData.currency = c;
         cDigits = CurrencyDigits(c);
     }
 
-    // Step 20.
+    // Step 21.
     var cd = GetOption(options, "currencyDisplay", "string", ["code", "symbol", "name"], "symbol");
-    if (style === "currency")
+    if (s === "currency")
         lazyNumberFormatData.currencyDisplay = cd;
 
-    // Steps 22-25.
-    var mnfdDefault, mxfdDefault;
-    if (style === "currency") {
-        mnfdDefault = cDigits;
-        mxfdDefault = cDigits;
-    } else {
-        mnfdDefault = 0;
-        mxfdDefault = style === "percent" ? 0 : 3;
+    // Step 23.
+    var mnid = GetNumberOption(options, "minimumIntegerDigits", 1, 21, 1);
+    lazyNumberFormatData.minimumIntegerDigits = mnid;
+
+    // Steps 25-26.
+    var mnfdDefault = (s === "currency") ? cDigits : 0;
+    var mnfd = GetNumberOption(options, "minimumFractionDigits", 0, 20, mnfdDefault);
+    lazyNumberFormatData.minimumFractionDigits = mnfd;
+
+    // Steps 28-29.
+    var mxfdDefault;
+    if (s === "currency")
+        mxfdDefault = std_Math_max(mnfd, cDigits);
+    else if (s === "percent")
+        mxfdDefault = std_Math_max(mnfd, 0);
+    else
+        mxfdDefault = std_Math_max(mnfd, 3);
+    var mxfd = GetNumberOption(options, "maximumFractionDigits", mnfd, 20, mxfdDefault);
+    lazyNumberFormatData.maximumFractionDigits = mxfd;
+
+    // Steps 31-32.
+    var mnsd = options.minimumSignificantDigits;
+    var mxsd = options.maximumSignificantDigits;
+
+    // Step 33.
+    if (mnsd !== undefined || mxsd !== undefined) {
+        mnsd = GetNumberOption(options, "minimumSignificantDigits", 1, 21, 1);
+        mxsd = GetNumberOption(options, "maximumSignificantDigits", mnsd, 21, 21);
+        lazyNumberFormatData.minimumSignificantDigits = mnsd;
+        lazyNumberFormatData.maximumSignificantDigits = mxsd;
     }
-    SetNumberFormatDigitOptions(lazyNumberFormatData, options, mnfdDefault, mxfdDefault);
 
-    // Steps 26.
+    // Step 34.
     var g = GetOption(options, "useGrouping", "boolean", undefined, true);
     lazyNumberFormatData.useGrouping = g;
 
-    // Steps 35-36.
+    // Step 43.
     //
     // We've done everything that must be done now: mark the lazy data as fully
     // computed and install it.
@@ -2026,6 +2002,43 @@ function InitializeNumberFormat(numberFormat, locales, options) {
 
 
 /**
+ * Mapping from currency codes to the number of decimal digits used for them.
+ * Default is 2 digits.
+ *
+ * Spec: ISO 4217 Currency and Funds Code List.
+ * http://www.currency-iso.org/en/home/tables/table-a1.html
+ */
+var currencyDigits = {
+    BHD: 3,
+    BIF: 0,
+    BYR: 0,
+    CLF: 4,
+    CLP: 0,
+    DJF: 0,
+    GNF: 0,
+    IQD: 3,
+    ISK: 0,
+    JOD: 3,
+    JPY: 0,
+    KMF: 0,
+    KRW: 0,
+    KWD: 3,
+    LYD: 3,
+    OMR: 3,
+    PYG: 0,
+    RWF: 0,
+    TND: 3,
+    UGX: 0,
+    UYI: 0,
+    VND: 0,
+    VUV: 0,
+    XAF: 0,
+    XOF: 0,
+    XPF: 0
+};
+
+
+/**
  * Returns the number of decimal digits to be used for the given currency.
  *
  * Spec: ECMAScript Internationalization API Specification, 11.1.1.
@@ -2106,7 +2119,7 @@ function numberFormatFormatToBind(value) {
 
     // Step 1.a.ii-iii.
     var x = ToNumber(value);
-    return intl_FormatNumber(this, x, /* formatToParts = */ false);
+    return intl_FormatNumber(this, x);
 }
 
 
@@ -2133,22 +2146,6 @@ function Intl_NumberFormat_format_get() {
     // Step 2.
     return internals.boundFormat;
 }
-_SetCanonicalName(Intl_NumberFormat_format_get, "get format");
-
-
-function Intl_NumberFormat_formatToParts(value) {
-    // Step 1.
-    var nf = this;
-
-    // Steps 2-3.
-    getNumberFormatInternals(nf, "formatToParts");
-
-    // Step 4.
-    var x = ToNumber(value);
-
-    // Step 5.
-    return intl_FormatNumber(nf, x, /* formatToParts = */ true);
-}
 
 
 /**
@@ -2290,6 +2287,26 @@ function getDateTimeFormatInternals(obj, methodName) {
     return internalProps;
 }
 
+/**
+ * Components of date and time formats and their values.
+ *
+ * Spec: ECMAScript Internationalization API Specification, 12.1.1.
+ */
+var dateTimeComponentValues = {
+    weekday: ["narrow", "short", "long"],
+    era: ["narrow", "short", "long"],
+    year: ["2-digit", "numeric"],
+    month: ["2-digit", "numeric", "narrow", "short", "long"],
+    day: ["2-digit", "numeric"],
+    hour: ["2-digit", "numeric"],
+    minute: ["2-digit", "numeric"],
+    second: ["2-digit", "numeric"],
+    timeZoneName: ["short", "long"]
+};
+
+
+var dateTimeComponents = std_Object_getOwnPropertyNames(dateTimeComponentValues);
+
 
 /**
  * Initializes an object as a DateTimeFormat.
@@ -2379,19 +2396,12 @@ function InitializeDateTimeFormat(dateTimeFormat, locales, options) {
     lazyDateTimeFormatData.formatOpt = formatOpt;
 
     // Step 19.
-    // 12.1, Table 4: Components of date and time formats.
-    formatOpt.weekday = GetOption(options, "weekday", "string", ["narrow", "short", "long"],
-                                  undefined);
-    formatOpt.era = GetOption(options, "era", "string", ["narrow", "short", "long"], undefined);
-    formatOpt.year = GetOption(options, "year", "string", ["2-digit", "numeric"], undefined);
-    formatOpt.month = GetOption(options, "month", "string",
-                                ["2-digit", "numeric", "narrow", "short", "long"], undefined);
-    formatOpt.day = GetOption(options, "day", "string", ["2-digit", "numeric"], undefined);
-    formatOpt.hour = GetOption(options, "hour", "string", ["2-digit", "numeric"], undefined);
-    formatOpt.minute = GetOption(options, "minute", "string", ["2-digit", "numeric"], undefined);
-    formatOpt.second = GetOption(options, "second", "string", ["2-digit", "numeric"], undefined);
-    formatOpt.timeZoneName = GetOption(options, "timeZoneName", "string", ["short", "long"],
-                                       undefined);
+    var i, prop;
+    for (i = 0; i < dateTimeComponents.length; i++) {
+        prop = dateTimeComponents[i];
+        var value = GetOption(options, prop, "string", dateTimeComponentValues[prop], undefined);
+        formatOpt[prop] = value;
+    }
 
     // Steps 20-21 provided by ICU - see comment after this function.
 
@@ -2659,6 +2669,7 @@ function ToDateTimeOptions(options, required, defaults) {
     return options;
 }
 
+
 /**
  * Compares the date and time components requested by options with the available
  * date and time formats in formats, and selects the best match according
@@ -2844,7 +2855,6 @@ function Intl_DateTimeFormat_format_get() {
     // Step 2.
     return internals.boundFormat;
 }
-_SetCanonicalName(Intl_DateTimeFormat_format_get, "get format");
 
 
 function Intl_DateTimeFormat_formatToParts() {
@@ -2980,232 +2990,6 @@ function resolveICUPattern(pattern, result) {
     }
 }
 
-/********** Intl.PluralRules **********/
-
-/**
- * PluralRules internal properties.
- *
- * Spec: ECMAScript 402 API, PluralRules, 1.3.3.
- */
-var pluralRulesInternalProperties = {
-    _availableLocales: null,
-    availableLocales: function()
-    {
-        var locales = this._availableLocales;
-        if (locales)
-            return locales;
-
-        locales = intl_PluralRules_availableLocales();
-        addSpecialMissingLanguageTags(locales);
-        return (this._availableLocales = locales);
-    }
-};
-
-/**
- * Compute an internal properties object from |lazyPluralRulesData|.
- */
-function resolvePluralRulesInternals(lazyPluralRulesData) {
-    assert(IsObject(lazyPluralRulesData), "lazy data not an object?");
-
-    var internalProps = std_Object_create(null);
-
-    var requestedLocales = lazyPluralRulesData.requestedLocales;
-
-    var PluralRules = pluralRulesInternalProperties;
-
-    // Step 13.
-    const r = ResolveLocale(callFunction(PluralRules.availableLocales, PluralRules),
-                          lazyPluralRulesData.requestedLocales,
-                          lazyPluralRulesData.opt,
-                          noRelevantExtensionKeys, undefined);
-
-    // Step 14.
-    internalProps.locale = r.locale;
-    internalProps.type = lazyPluralRulesData.type;
-
-    internalProps.pluralCategories = intl_GetPluralCategories(
-        internalProps.locale,
-        internalProps.type);
-
-    internalProps.minimumIntegerDigits = lazyPluralRulesData.minimumIntegerDigits;
-    internalProps.minimumFractionDigits = lazyPluralRulesData.minimumFractionDigits;
-    internalProps.maximumFractionDigits = lazyPluralRulesData.maximumFractionDigits;
-
-    if ("minimumSignificantDigits" in lazyPluralRulesData) {
-        assert("maximumSignificantDigits" in lazyPluralRulesData, "min/max sig digits mismatch");
-        internalProps.minimumSignificantDigits = lazyPluralRulesData.minimumSignificantDigits;
-        internalProps.maximumSignificantDigits = lazyPluralRulesData.maximumSignificantDigits;
-    }
-
-    return internalProps;
-}
-
-/**
- * Returns an object containing the PluralRules internal properties of |obj|,
- * or throws a TypeError if |obj| isn't PluralRules-initialized.
- */
-function getPluralRulesInternals(obj, methodName) {
-    var internals = getIntlObjectInternals(obj, "PluralRules", methodName);
-    assert(internals.type === "PluralRules", "bad type escaped getIntlObjectInternals");
-
-    var internalProps = maybeInternalProperties(internals);
-    if (internalProps)
-        return internalProps;
-
-    internalProps = resolvePluralRulesInternals(internals.lazyData);
-    setInternalProperties(internals, internalProps);
-    return internalProps;
-}
-
-/**
- * Initializes an object as a PluralRules.
- *
- * This method is complicated a moderate bit by its implementing initialization
- * as a *lazy* concept.  Everything that must happen now, does -- but we defer
- * all the work we can until the object is actually used as a PluralRules.
- * This later work occurs in |resolvePluralRulesInternals|; steps not noted
- * here occur there.
- *
- * Spec: ECMAScript 402 API, PluralRules, 1.1.1.
- */
-function InitializePluralRules(pluralRules, locales, options) {
-    assert(IsObject(pluralRules), "InitializePluralRules");
-
-    // Step 1.
-    if (isInitializedIntlObject(pluralRules))
-        ThrowTypeError(JSMSG_INTL_OBJECT_REINITED);
-
-    let internals = initializeIntlObject(pluralRules);
-
-    // Lazy PluralRules data has the following structure:
-    //
-    //   {
-    //     requestedLocales: List of locales,
-    //     type: "cardinal" / "ordinal",
-    //
-    //     opt: // opt object computer in InitializePluralRules
-    //       {
-    //         localeMatcher: "lookup" / "best fit",
-    //       }
-    //
-    //     minimumIntegerDigits: integer ∈ [1, 21],
-    //     minimumFractionDigits: integer ∈ [0, 20],
-    //     maximumFractionDigits: integer ∈ [0, 20],
-    //
-    //     // optional
-    //     minimumSignificantDigits: integer ∈ [1, 21],
-    //     maximumSignificantDigits: integer ∈ [1, 21],
-    //   }
-    //
-    // Note that lazy data is only installed as a final step of initialization,
-    // so every PluralRules lazy data object has *all* these properties, never a
-    // subset of them.
-    const lazyPluralRulesData = std_Object_create(null);
-
-    // Step 3.
-    let requestedLocales = CanonicalizeLocaleList(locales);
-    lazyPluralRulesData.requestedLocales = requestedLocales;
-
-    // Steps 4-5.
-    if (options === undefined)
-        options = {};
-    else
-        options = ToObject(options);
-
-    // Step 6.
-    const type = GetOption(options, "type", "string", ["cardinal", "ordinal"], "cardinal");
-    lazyPluralRulesData.type = type;
-
-    // Step 8.
-    let opt = new Record();
-    lazyPluralRulesData.opt = opt;
-
-    // Steps 9-10.
-    let matcher = GetOption(options, "localeMatcher", "string", ["lookup", "best fit"], "best fit");
-    opt.localeMatcher = matcher;
-
-    // Steps 11-12.
-    SetNumberFormatDigitOptions(lazyPluralRulesData, options, 0, 3);
-
-    setLazyData(internals, "PluralRules", lazyPluralRulesData)
-}
-
-/**
- * Returns the subset of the given locale list for which this locale list has a
- * matching (possibly fallback) locale. Locales appear in the same order in the
- * returned list as in the input list.
- *
- * Spec: ECMAScript 402 API, PluralRules, 1.3.2.
- */
-function Intl_PluralRules_supportedLocalesOf(locales /*, options*/) {
-    var options = arguments.length > 1 ? arguments[1] : undefined;
-
-    // Step 1.
-    var availableLocales = callFunction(pluralRulesInternalProperties.availableLocales,
-                                        pluralRulesInternalProperties);
-    // Step 2.
-    let requestedLocales = CanonicalizeLocaleList(locales);
-
-    // Step 3.
-    return SupportedLocales(availableLocales, requestedLocales, options);
-}
-
-/**
- * Returns a String value representing the plural category matching
- * the number passed as value according to the
- * effective locale and the formatting options of this PluralRules.
- *
- * Spec: ECMAScript 402 API, PluralRules, 1.4.3.
- */
-function Intl_PluralRules_select(value) {
-    // Step 1.
-    let pluralRules = this;
-    // Step 2.
-    let internals = getPluralRulesInternals(pluralRules, "select");
-
-    // Steps 3-4.
-    let n = ToNumber(value);
-
-    // Step 5.
-    return intl_SelectPluralRule(pluralRules, n);
-}
-
-/**
- * Returns the resolved options for a PluralRules object.
- *
- * Spec: ECMAScript 402 API, PluralRules, 1.4.4.
- */
-function Intl_PluralRules_resolvedOptions() {
-    var internals = getPluralRulesInternals(this, "resolvedOptions");
-
-    var internalsPluralCategories = internals.pluralCategories;
-    var pluralCategories = [];
-    for (var i = 0; i < internalsPluralCategories.length; i++)
-        _DefineDataProperty(pluralCategories, i, internalsPluralCategories[i]);
-
-    var result = {
-        locale: internals.locale,
-        type: internals.type,
-        pluralCategories,
-        minimumIntegerDigits: internals.minimumIntegerDigits,
-        minimumFractionDigits: internals.minimumFractionDigits,
-        maximumFractionDigits: internals.maximumFractionDigits,
-    };
-
-    var optionalProperties = [
-        "minimumSignificantDigits",
-        "maximumSignificantDigits"
-    ];
-
-    for (var i = 0; i < optionalProperties.length; i++) {
-        var p = optionalProperties[i];
-        if (callFunction(std_Object_hasOwnProperty, internals, p))
-            _DefineDataProperty(result, p, internals[p]);
-    }
-    return result;
-}
-
-
 function Intl_getCanonicalLocales(locales) {
   let codes = CanonicalizeLocaleList(locales);
   let result = [];
@@ -3362,5 +3146,5 @@ function Intl_getDisplayNames(locales, options) {
 
     // 24. Return result.
     return result;
-}
 
+}
diff --git a/js/src/builtin/IntlTimeZoneData.h b/js/src/builtin/IntlTimeZoneData.h
index f92c583df..fa808c0b9 100644
--- a/js/src/builtin/IntlTimeZoneData.h
+++ b/js/src/builtin/IntlTimeZoneData.h
@@ -1,5 +1,5 @@
 // Generated by make_intl_data.py. DO NOT EDIT.
-// tzdata version = 2018c
+// tzdata version = 2018e
 
 #ifndef builtin_IntlTimeZoneData_h
 #define builtin_IntlTimeZoneData_h
diff --git a/js/src/builtin/Map.js b/js/src/builtin/Map.js
index 580629a13..434cd6529 100644
--- a/js/src/builtin/Map.js
+++ b/js/src/builtin/Map.js
@@ -62,8 +62,8 @@ function MapIteratorNext() {
     var O = this;
 
     // Steps 2-3.
-    if (!IsObject(O) || !IsMapIterator(O))
-        return callFunction(CallMapIteratorMethodIfWrapped, O, "MapIteratorNext");
+    if (!IsObject(O) || (O = GuardToMapIterator(O)) === null)
+        return callFunction(CallMapIteratorMethodIfWrapped, this, "MapIteratorNext");
 
     // Steps 4-5 (implemented in _GetNextMapEntryForIterator).
     // Steps 8-9 (omitted).
@@ -82,7 +82,7 @@ function MapIteratorNext() {
         // Steps 10.b-c (omitted).
 
         // Step 6.
-        var itemKind = UnsafeGetInt32FromReservedSlot(this, ITERATOR_SLOT_ITEM_KIND);
+        var itemKind = UnsafeGetInt32FromReservedSlot(O, ITERATOR_SLOT_ITEM_KIND);
 
         var result;
         if (itemKind === ITEM_KIND_KEY) {
diff --git a/js/src/builtin/Set.js b/js/src/builtin/Set.js
index 9af6cf8d1..e2571e66a 100644
--- a/js/src/builtin/Set.js
+++ b/js/src/builtin/Set.js
@@ -64,8 +64,8 @@ function SetIteratorNext() {
     var O = this;
 
     // Steps 2-3.
-    if (!IsObject(O) || !IsSetIterator(O))
-        return callFunction(CallSetIteratorMethodIfWrapped, O, "SetIteratorNext");
+    if (!IsObject(O) || (O = GuardToSetIterator(O)) === null)
+        return callFunction(CallSetIteratorMethodIfWrapped, this, "SetIteratorNext");
 
     // Steps 4-5 (implemented in _GetNextSetEntryForIterator).
     // Steps 8-9 (omitted).
@@ -83,7 +83,7 @@ function SetIteratorNext() {
         // Steps 10.b-c (omitted).
 
         // Step 6.
-        var itemKind = UnsafeGetInt32FromReservedSlot(this, ITERATOR_SLOT_ITEM_KIND);
+        var itemKind = UnsafeGetInt32FromReservedSlot(O, ITERATOR_SLOT_ITEM_KIND);
 
         var result;
         if (itemKind === ITEM_KIND_VALUE) {
diff --git a/js/src/builtin/String.js b/js/src/builtin/String.js
index 4202d0de6..e5b2ad552 100644
--- a/js/src/builtin/String.js
+++ b/js/src/builtin/String.js
@@ -529,16 +529,17 @@ function String_iterator() {
 }
 
 function StringIteratorNext() {
-    if (!IsObject(this) || !IsStringIterator(this)) {
+    var obj;
+    if (!IsObject(this) || (obj = GuardToStringIterator(this)) === null) {
         return callFunction(CallStringIteratorMethodIfWrapped, this,
                             "StringIteratorNext");
     }
 
-    var S = UnsafeGetStringFromReservedSlot(this, ITERATOR_SLOT_TARGET);
+    var S = UnsafeGetStringFromReservedSlot(obj, ITERATOR_SLOT_TARGET);
     // We know that JSString::MAX_LENGTH <= INT32_MAX (and assert this in
     // SelfHostring.cpp) so our current index can never be anything other than
     // an Int32Value.
-    var index = UnsafeGetInt32FromReservedSlot(this, ITERATOR_SLOT_NEXT_INDEX);
+    var index = UnsafeGetInt32FromReservedSlot(obj, ITERATOR_SLOT_NEXT_INDEX);
     var size = S.length;
     var result = { value: undefined, done: false };
 
@@ -556,7 +557,7 @@ function StringIteratorNext() {
         }
     }
 
-    UnsafeSetReservedSlot(this, ITERATOR_SLOT_NEXT_INDEX, index + charCount);
+    UnsafeSetReservedSlot(obj, ITERATOR_SLOT_NEXT_INDEX, index + charCount);
     result.value = callFunction(String_substring, S, index, index + charCount);
 
     return result;
@@ -659,11 +660,7 @@ function String_static_localeCompare(str1, str2) {
         ThrowTypeError(JSMSG_MISSING_FUN_ARG, 0, "String.localeCompare");
     var locales = arguments.length > 2 ? arguments[2] : undefined;
     var options = arguments.length > 3 ? arguments[3] : undefined;
-#if EXPOSE_INTL_API
     return callFunction(String_localeCompare, str1, str2, locales, options);
-#else
-    return callFunction(std_String_localeCompare, str1, str2, locales, options);
-#endif
 }
 
 // ES6 draft 2014-04-27 B.2.3.3
@@ -855,14 +852,12 @@ function String_static_toLocaleUpperCase(string) {
     return callFunction(std_String_toLocaleUpperCase, string);
 }
 
-#if EXPOSE_INTL_API
 function String_static_normalize(string) {
     if (arguments.length < 1)
         ThrowTypeError(JSMSG_MISSING_FUN_ARG, 0, 'String.normalize');
     var form = arguments.length > 1 ? arguments[1] : undefined;
     return callFunction(std_String_normalize, string, form);
 }
-#endif
 
 function String_static_concat(string, arg1) {
     if (arguments.length < 1)
diff --git a/js/src/builtin/TestingFunctions.cpp b/js/src/builtin/TestingFunctions.cpp
index a14f9ba69..373b6c9ed 100644
--- a/js/src/builtin/TestingFunctions.cpp
+++ b/js/src/builtin/TestingFunctions.cpp
@@ -236,11 +236,7 @@ GetBuildConfiguration(JSContext* cx, unsigned argc, Value* vp)
     if (!JS_SetProperty(cx, info, "binary-data", value))
         return false;
 
-#ifdef EXPOSE_INTL_API
     value = BooleanValue(true);
-#else
-    value = BooleanValue(false);
-#endif
     if (!JS_SetProperty(cx, info, "intl-api", value))
         return false;
 
@@ -2092,7 +2088,7 @@ class CloneBufferObject : public NativeObject {
         Rooted<CloneBufferObject*> obj(cx, Create(cx));
         if (!obj)
             return nullptr;
-        auto data = js::MakeUnique<JSStructuredCloneData>();
+        auto data = js::MakeUnique<JSStructuredCloneData>(buffer->scope());
         if (!data) {
             ReportOutOfMemory(cx);
             return nullptr;
@@ -2145,8 +2141,11 @@ class CloneBufferObject : public NativeObject {
             return false;
         size_t nbytes = JS_GetStringLength(args[0].toString());
         MOZ_ASSERT(nbytes % sizeof(uint64_t) == 0);
-        auto buf = js::MakeUnique<JSStructuredCloneData>(nbytes, nbytes, nbytes);
-        js_memcpy(buf->Start(), str, nbytes);
+        auto buf = js::MakeUnique<JSStructuredCloneData>(JS::StructuredCloneScope::DifferentProcess);
+        if (!buf->AppendBytes(str, nbytes)) {
+            ReportOutOfMemory(cx);
+            return false;
+        }
         JS_free(cx, str);
         obj->setData(buf.release());
 
@@ -2190,7 +2189,7 @@ class CloneBufferObject : public NativeObject {
             ReportOutOfMemory(cx);
             return false;
         }
-        auto iter = obj->data()->Iter();
+        auto iter = obj->data()->Start();
         obj->data()->ReadBytes(iter, buffer.get(), size);
         JSString* str = JS_NewStringCopyN(cx, buffer.get(), size);
         if (!str)
@@ -2248,6 +2247,8 @@ ParseCloneScope(JSContext* cx, HandleString str)
         scope.emplace(JS::StructuredCloneScope::SameProcessDifferentThread);
     else if (strcmp(scopeStr.ptr(), "DifferentProcess") == 0)
         scope.emplace(JS::StructuredCloneScope::DifferentProcess);
+    else if (strcmp(scopeStr.ptr(), "DifferentProcessForIndexedDB") == 0)
+        scope.emplace(JS::StructuredCloneScope::DifferentProcessForIndexedDB);
 
     return scope;
 }
@@ -4374,19 +4375,22 @@ JS_FN_HELP("rejectPromise", RejectPromise, 2, 0,
 "  clone buffer object. 'policy' may be an options hash. Valid keys:\n"
 "    'SharedArrayBuffer' - either 'allow' (the default) or 'deny'\n"
 "    to specify whether SharedArrayBuffers may be serialized.\n"
-"\n"
-"    'scope' - SameProcessSameThread, SameProcessDifferentThread, or\n"
-"    DifferentProcess. Determines how some values will be serialized.\n"
-"    Clone buffers may only be deserialized with a compatible scope."),
+"    'scope' - SameProcessSameThread, SameProcessDifferentThread,\n"
+"      DifferentProcess, or DifferentProcessForIndexedDB. Determines how some\n"
+"      values will be serialized. Clone buffers may only be deserialized with a\n"
+"      compatible scope. NOTE - For DifferentProcess/DifferentProcessForIndexedDB,\n"
+"      must also set SharedArrayBuffer:'deny' if data contains any shared memory\n"
+"      object."),
 
     JS_FN_HELP("deserialize", Deserialize, 1, 0,
 "deserialize(clonebuffer[, opts])",
 "  Deserialize data generated by serialize. 'opts' is an options hash with one\n"
 "  recognized key 'scope', which limits the clone buffers that are considered\n"
 "  valid. Allowed values: 'SameProcessSameThread', 'SameProcessDifferentThread',\n"
-"  and 'DifferentProcess'. So for example, a DifferentProcess clone buffer\n"
-"  may be deserialized in any scope, but a SameProcessSameThread clone buffer\n"
-"  cannot be deserialized in a DifferentProcess scope."),
+"  'DifferentProcess', and 'DifferentProcessForIndexedDB'. So for example, a\n"
+"  DifferentProcessForIndexedDB clone buffer may be deserialized in any scope, but\n"
+"  a SameProcessSameThread clone buffer cannot be deserialized in a\n"
+"  DifferentProcess scope."),
 
     JS_FN_HELP("detachArrayBuffer", DetachArrayBuffer, 1, 0,
 "detachArrayBuffer(buffer)",
diff --git a/js/src/builtin/TypedArray.js b/js/src/builtin/TypedArray.js
index a2205dc92..a1934051d 100644
--- a/js/src/builtin/TypedArray.js
+++ b/js/src/builtin/TypedArray.js
@@ -1232,11 +1232,7 @@ function TypedArrayToLocaleString(locales = undefined, options = undefined) {
     // Steps 6-7.
     // Omit the 'if' clause in step 6, since typed arrays can't have undefined
     // or null elements.
-#if EXPOSE_INTL_API
     var R = ToString(callContentFunction(firstElement.toLocaleString, firstElement, locales, options));
-#else
-    var R = ToString(callContentFunction(firstElement.toLocaleString, firstElement));
-#endif
 
     // Step 3 (reordered).
     // We don't (yet?) implement locale-dependent separators.
@@ -1258,11 +1254,7 @@ function TypedArrayToLocaleString(locales = undefined, options = undefined) {
         // the error message. So despite bug 1079853, we can skip step 9.c.
 
         // Step 9.d.
-#if EXPOSE_INTL_API
         R = ToString(callContentFunction(nextElement.toLocaleString, nextElement, locales, options));
-#else
-        R = ToString(callContentFunction(nextElement.toLocaleString, nextElement));
-#endif
 
         // Step 9.e.
         R = S + R;
diff --git a/js/src/gc/GCRuntime.h b/js/src/gc/GCRuntime.h
index 19737c9ee..5c2576efd 100644
--- a/js/src/gc/GCRuntime.h
+++ b/js/src/gc/GCRuntime.h
@@ -73,7 +73,7 @@ class ChunkPool
 
 // Performs extra allocation off the main thread so that when memory is
 // required on the main thread it will already be available and waiting.
-class BackgroundAllocTask : public GCParallelTask
+class BackgroundAllocTask : public GCParallelTaskHelper<BackgroundAllocTask>
 {
     // Guarded by the GC lock.
     JSRuntime* runtime;
@@ -85,12 +85,11 @@ class BackgroundAllocTask : public GCParallelTask
     BackgroundAllocTask(JSRuntime* rt, ChunkPool& pool);
     bool enabled() const { return enabled_; }
 
-  protected:
-    void run() override;
+    void run();
 };
 
-// Search the provided Chunks for free arenas and decommit them.
-class BackgroundDecommitTask : public GCParallelTask
+// Search the provided Chunks for free arenas and recommit them.
+class BackgroundDecommitTask : public GCParallelTaskHelper<BackgroundDecommitTask>
 {
   public:
     using ChunkVector = mozilla::Vector<Chunk*>;
@@ -98,8 +97,7 @@ class BackgroundDecommitTask : public GCParallelTask
     explicit BackgroundDecommitTask(JSRuntime *rt) : runtime(rt) {}
     void setChunksToScan(ChunkVector &chunks);
 
-  protected:
-    void run() override;
+    void run();
 
   private:
     JSRuntime* runtime;
@@ -1171,8 +1169,10 @@ class GCRuntime
     /*
      * Concurrent sweep infrastructure.
      */
-    void startTask(GCParallelTask& task, gcstats::Phase phase, AutoLockHelperThreadState& locked);
-    void joinTask(GCParallelTask& task, gcstats::Phase phase, AutoLockHelperThreadState& locked);
+    void startTask(GCParallelTask& task, gcstats::Phase phase,
+                   AutoLockHelperThreadState& locked);
+    void joinTask(GCParallelTask& task, gcstats::Phase phase,
+                  AutoLockHelperThreadState& locked);
 
     /*
      * List head of arenas allocated during the sweep phase.
diff --git a/js/src/gc/Nursery.cpp b/js/src/gc/Nursery.cpp
index aa50bf29e..55ca5a059 100644
--- a/js/src/gc/Nursery.cpp
+++ b/js/src/gc/Nursery.cpp
@@ -43,19 +43,19 @@ using mozilla::PodZero;
 
 static const uintptr_t CanaryMagicValue = 0xDEADB15D;
 
-struct js::Nursery::FreeMallocedBuffersTask : public GCParallelTask
+struct js::Nursery::FreeMallocedBuffersTask : public GCParallelTaskHelper<FreeMallocedBuffersTask>
 {
     explicit FreeMallocedBuffersTask(FreeOp* fop) : fop_(fop) {}
     bool init() { return buffers_.init(); }
     void transferBuffersToFree(MallocedBuffersSet& buffersToFree,
                                const AutoLockHelperThreadState& lock);
-    ~FreeMallocedBuffersTask() override { join(); }
+    ~FreeMallocedBuffersTask() { join(); }
+
+    void run();
 
   private:
     FreeOp* fop_;
     MallocedBuffersSet buffers_;
-
-    virtual void run() override;
 };
 
 struct js::Nursery::SweepAction
diff --git a/js/src/gc/Statistics.h b/js/src/gc/Statistics.h
index c9e5871e3..ca1969b2c 100644
--- a/js/src/gc/Statistics.h
+++ b/js/src/gc/Statistics.h
@@ -22,9 +22,6 @@
 using mozilla::Maybe;
 
 namespace js {
-
-class GCParallelTask;
-
 namespace gcstats {
 
 enum Phase : uint8_t {
diff --git a/js/src/gdb/moz.build b/js/src/gdb/moz.build
index 681f9807c..faa69eb7b 100644
--- a/js/src/gdb/moz.build
+++ b/js/src/gdb/moz.build
@@ -34,7 +34,7 @@ USE_LIBS += [
     'static:js',
 ]
 
-if CONFIG['ENABLE_INTL_API'] and CONFIG['MOZ_ICU_DATA_ARCHIVE']:
+if CONFIG['MOZ_ICU_DATA_ARCHIVE']:
     # The ICU libraries linked into libmozjs will not include the ICU data,
     # so link it directly.
     USE_LIBS += ['icudata']
diff --git a/js/src/jit/BaselineFrameInfo.h b/js/src/jit/BaselineFrameInfo.h
index 13bf0358d..1691270ac 100644
--- a/js/src/jit/BaselineFrameInfo.h
+++ b/js/src/jit/BaselineFrameInfo.h
@@ -67,7 +67,7 @@ class StackValue
 
     union {
         struct {
-            Value v;
+            JS::UninitializedValue v;
         } constant;
         struct {
             mozilla::AlignedStorage2<ValueOperand> reg;
@@ -112,7 +112,7 @@ class StackValue
     }
     Value constant() const {
         MOZ_ASSERT(kind_ == Constant);
-        return data.constant.v;
+        return data.constant.v.asValueRef();
     }
     ValueOperand reg() const {
         MOZ_ASSERT(kind_ == Register);
diff --git a/js/src/jit/CodeGenerator.cpp b/js/src/jit/CodeGenerator.cpp
index 7b2f8214b..16d026092 100644
--- a/js/src/jit/CodeGenerator.cpp
+++ b/js/src/jit/CodeGenerator.cpp
@@ -11529,6 +11529,32 @@ CodeGenerator::visitHasClass(LHasClass* ins)
 }
 
 void
+CodeGenerator::visitGuardToClass(LGuardToClass* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    Register output = ToRegister(ins->output());
+    Register temp = ToRegister(ins->temp());
+
+    Label notEqual;
+
+    masm.branchTestObjClass(Assembler::NotEqual, lhs, temp, ins->mir()->getClass(), &notEqual);
+    masm.mov(lhs, output);
+
+    if (ins->mir()->type() == MIRType::Object) {
+        // Can't return null-return here, so bail
+        bailoutFrom(&notEqual, ins->snapshot());
+    } else {
+        Label done;
+        masm.jump(&done);
+
+        masm.bind(&notEqual);
+        masm.mov(ImmPtr(0), output);
+
+        masm.bind(&done);
+    }
+}
+
+void
 CodeGenerator::visitWasmParameter(LWasmParameter* lir)
 {
 }
diff --git a/js/src/jit/CodeGenerator.h b/js/src/jit/CodeGenerator.h
index d3126651b..b226f6cc9 100644
--- a/js/src/jit/CodeGenerator.h
+++ b/js/src/jit/CodeGenerator.h
@@ -377,6 +377,7 @@ class CodeGenerator final : public CodeGeneratorSpecific
     void visitIsObject(LIsObject* lir);
     void visitIsObjectAndBranch(LIsObjectAndBranch* lir);
     void visitHasClass(LHasClass* lir);
+    void visitGuardToClass(LGuardToClass* lir);
     void visitWasmParameter(LWasmParameter* lir);
     void visitWasmParameterI64(LWasmParameterI64* lir);
     void visitWasmReturn(LWasmReturn* ret);
diff --git a/js/src/jit/InlinableNatives.h b/js/src/jit/InlinableNatives.h
index 15352c04f..23d3143a7 100644
--- a/js/src/jit/InlinableNatives.h
+++ b/js/src/jit/InlinableNatives.h
@@ -117,13 +117,15 @@
     _(IntrinsicDefineDataProperty)  \
     _(IntrinsicObjectHasPrototype)  \
                                     \
-    _(IntrinsicIsArrayIterator)     \
-    _(IntrinsicIsMapIterator)       \
-    _(IntrinsicIsSetIterator)       \
-    _(IntrinsicIsStringIterator)    \
+    _(IntrinsicGuardToArrayIterator) \
+    _(IntrinsicGuardToMapIterator)  \
+    _(IntrinsicGuardToSetIterator)  \
+    _(IntrinsicGuardToStringIterator) \
                                     \
+    _(IntrinsicGuardToMapObject)    \
     _(IntrinsicGetNextMapEntryForIterator) \
                                     \
+    _(IntrinsicGuardToSetObject)    \
     _(IntrinsicGetNextSetEntryForIterator) \
                                     \
     _(IntrinsicArrayBufferByteLength) \
diff --git a/js/src/jit/IonBuilder.h b/js/src/jit/IonBuilder.h
index 35ad120f7..f24ef30c8 100644
--- a/js/src/jit/IonBuilder.h
+++ b/js/src/jit/IonBuilder.h
@@ -969,6 +969,7 @@ class IonBuilder
                                   const Class* clasp2 = nullptr,
                                   const Class* clasp3 = nullptr,
                                   const Class* clasp4 = nullptr);
+    InliningStatus inlineGuardToClass(CallInfo& callInfo, const Class* clasp);
     InliningStatus inlineIsConstructing(CallInfo& callInfo);
     InliningStatus inlineSubstringKernel(CallInfo& callInfo);
     InliningStatus inlineObjectHasPrototype(CallInfo& callInfo);
diff --git a/js/src/jit/JitFrameIterator.h b/js/src/jit/JitFrameIterator.h
index ba5efef6a..3620badbd 100644
--- a/js/src/jit/JitFrameIterator.h
+++ b/js/src/jit/JitFrameIterator.h
@@ -322,9 +322,7 @@ class RInstructionResults
 
     MOZ_MUST_USE bool init(JSContext* cx, uint32_t numResults);
     bool isInitialized() const;
-#ifdef DEBUG
     size_t length() const;
-#endif
 
     JitFrameLayout* frame() const;
 
diff --git a/js/src/jit/JitFrames.cpp b/js/src/jit/JitFrames.cpp
index f11f17225..019be46dd 100644
--- a/js/src/jit/JitFrames.cpp
+++ b/js/src/jit/JitFrames.cpp
@@ -1688,13 +1688,11 @@ RInstructionResults::isInitialized() const
     return initialized_;
 }
 
-#ifdef DEBUG
 size_t
 RInstructionResults::length() const
 {
     return results_->length();
 }
-#endif
 
 JitFrameLayout*
 RInstructionResults::frame() const
@@ -2150,7 +2148,7 @@ SnapshotIterator::initInstructionResults(MaybeReadFallback& fallback)
     }
 
     MOZ_ASSERT(results->isInitialized());
-    MOZ_ASSERT(results->length() == recover_.numInstructions() - 1);
+    MOZ_RELEASE_ASSERT(results->length() == recover_.numInstructions() - 1);
     instructionResults_ = results;
     return true;
 }
diff --git a/js/src/jit/Lowering.cpp b/js/src/jit/Lowering.cpp
index 730697163..709de9987 100644
--- a/js/src/jit/Lowering.cpp
+++ b/js/src/jit/Lowering.cpp
@@ -4171,6 +4171,16 @@ LIRGenerator::visitHasClass(MHasClass* ins)
 }
 
 void
+LIRGenerator::visitGuardToClass(MGuardToClass* ins)
+{
+    MOZ_ASSERT(ins->object()->type() == MIRType::Object);
+    MOZ_ASSERT(ins->type() == MIRType::ObjectOrNull|| ins->type() == MIRType::Object);
+    LGuardToClass* lir = new(alloc()) LGuardToClass(useRegister(ins->object()), temp());
+    assignSnapshot(lir, Bailout_TypeBarrierO);
+    define(lir, ins);
+}
+
+void
 LIRGenerator::visitWasmAddOffset(MWasmAddOffset* ins)
 {
     MOZ_ASSERT(ins->base()->type() == MIRType::Int32);
diff --git a/js/src/jit/Lowering.h b/js/src/jit/Lowering.h
index b2805cb7a..9b4095aec 100644
--- a/js/src/jit/Lowering.h
+++ b/js/src/jit/Lowering.h
@@ -289,6 +289,7 @@ class LIRGenerator : public LIRGeneratorSpecific
     void visitIsConstructor(MIsConstructor* ins);
     void visitIsObject(MIsObject* ins);
     void visitHasClass(MHasClass* ins);
+    void visitGuardToClass(MGuardToClass* ins);
     void visitWasmAddOffset(MWasmAddOffset* ins);
     void visitWasmBoundsCheck(MWasmBoundsCheck* ins);
     void visitWasmLoadGlobalVar(MWasmLoadGlobalVar* ins);
diff --git a/js/src/jit/MCallOptimize.cpp b/js/src/jit/MCallOptimize.cpp
index 293253253..736c6c892 100644
--- a/js/src/jit/MCallOptimize.cpp
+++ b/js/src/jit/MCallOptimize.cpp
@@ -280,24 +280,28 @@ IonBuilder::inlineNativeCall(CallInfo& callInfo, JSFunction* target)
         return inlineIsConstructing(callInfo);
       case InlinableNative::IntrinsicSubstringKernel:
         return inlineSubstringKernel(callInfo);
-      case InlinableNative::IntrinsicIsArrayIterator:
-        return inlineHasClass(callInfo, &ArrayIteratorObject::class_);
-      case InlinableNative::IntrinsicIsMapIterator:
-        return inlineHasClass(callInfo, &MapIteratorObject::class_);
-      case InlinableNative::IntrinsicIsSetIterator:
-        return inlineHasClass(callInfo, &SetIteratorObject::class_);
-      case InlinableNative::IntrinsicIsStringIterator:
-        return inlineHasClass(callInfo, &StringIteratorObject::class_);
+      case InlinableNative::IntrinsicGuardToArrayIterator:
+        return inlineGuardToClass(callInfo, &ArrayIteratorObject::class_);
+      case InlinableNative::IntrinsicGuardToMapIterator:
+        return inlineGuardToClass(callInfo, &MapIteratorObject::class_);
+      case InlinableNative::IntrinsicGuardToSetIterator:
+        return inlineGuardToClass(callInfo, &SetIteratorObject::class_);
+      case InlinableNative::IntrinsicGuardToStringIterator:
+        return inlineGuardToClass(callInfo, &StringIteratorObject::class_);
       case InlinableNative::IntrinsicDefineDataProperty:
         return inlineDefineDataProperty(callInfo);
       case InlinableNative::IntrinsicObjectHasPrototype:
         return inlineObjectHasPrototype(callInfo);
 
       // Map intrinsics.
+      case InlinableNative::IntrinsicGuardToMapObject:
+        return inlineGuardToClass(callInfo, &MapObject::class_);
       case InlinableNative::IntrinsicGetNextMapEntryForIterator:
         return inlineGetNextEntryForIterator(callInfo, MGetNextEntryForIterator::Map);
 
       // Set intrinsics.
+      case InlinableNative::IntrinsicGuardToSetObject:
+        return inlineGuardToClass(callInfo, &SetObject::class_);
       case InlinableNative::IntrinsicGetNextSetEntryForIterator:
         return inlineGetNextEntryForIterator(callInfo, MGetNextEntryForIterator::Set);
 
@@ -2218,6 +2222,37 @@ IonBuilder::inlineHasClass(CallInfo& callInfo,
 }
 
 IonBuilder::InliningStatus
+IonBuilder::inlineGuardToClass(CallInfo& callInfo, const Class* clasp)
+{
+    MOZ_ASSERT(!callInfo.constructing());
+    MOZ_ASSERT(callInfo.argc() == 1);
+
+    if (callInfo.getArg(0)->type() != MIRType::Object)
+        return InliningStatus_NotInlined;
+
+    if (getInlineReturnType() != MIRType::ObjectOrNull &&
+        getInlineReturnType() != MIRType::Object)
+    {
+        return InliningStatus_NotInlined;
+    }
+    
+    TemporaryTypeSet* types = callInfo.getArg(0)->resultTypeSet();
+    const Class* knownClass = types ? types->getKnownClass(constraints()) : nullptr;
+
+    if (knownClass && knownClass == clasp) {
+        current->push(callInfo.getArg(0));
+    } else {
+        MGuardToClass* guardToClass = MGuardToClass::New(alloc(), callInfo.getArg(0),
+                                                         clasp, getInlineReturnType());
+        current->add(guardToClass);
+        current->push(guardToClass);
+    }
+
+    callInfo.setImplicitlyUsedUnchecked();
+    return InliningStatus_Inlined;
+}
+
+IonBuilder::InliningStatus
 IonBuilder::inlineGetNextEntryForIterator(CallInfo& callInfo, MGetNextEntryForIterator::Mode mode)
 {
     if (callInfo.argc() != 2 || callInfo.constructing()) {
diff --git a/js/src/jit/MIR.h b/js/src/jit/MIR.h
index 2de91e2df..6ec05af76 100644
--- a/js/src/jit/MIR.h
+++ b/js/src/jit/MIR.h
@@ -13192,6 +13192,48 @@ class MHasClass
     }
 };
 
+class MGuardToClass
+    : public MUnaryInstruction,
+      public SingleObjectPolicy::Data
+{
+    const Class* class_;
+
+    MGuardToClass(MDefinition* object, const Class* clasp, MIRType resultType)
+      : MUnaryInstruction(object)
+      , class_(clasp)
+    {
+        MOZ_ASSERT(object->type() == MIRType::Object ||
+                   (object->type() == MIRType::Value && object->mightBeType(MIRType::Object)));
+        MOZ_ASSERT(resultType == MIRType::Object || resultType == MIRType::ObjectOrNull);
+        setResultType(resultType);
+        setMovable();
+        if (resultType == MIRType::Object) {
+            // We will bail out if the class type is incorrect,
+            // so we need to ensure we don't eliminate this instruction
+            setGuard();
+        }
+    }
+
+  public:
+    INSTRUCTION_HEADER(GuardToClass)
+    TRIVIAL_NEW_WRAPPERS
+    NAMED_OPERANDS((0, object))
+
+    const Class* getClass() const {
+        return class_;
+    }
+    AliasSet getAliasSet() const override {
+        return AliasSet::None();
+    }
+    bool congruentTo(const MDefinition* ins) const override {
+        if (!ins->isGuardToClass())
+            return false;
+        if (getClass() != ins->toGuardToClass()->getClass())
+            return false;
+        return congruentIfOperandsEqual(ins);
+    }
+};
+
 class MCheckReturn
   : public MBinaryInstruction,
     public BoxInputsPolicy::Data
diff --git a/js/src/jit/MOpcodes.h b/js/src/jit/MOpcodes.h
index bb2ab8190..fddc1e637 100644
--- a/js/src/jit/MOpcodes.h
+++ b/js/src/jit/MOpcodes.h
@@ -272,6 +272,7 @@ namespace jit {
     _(IsCallable)                                                           \
     _(IsObject)                                                             \
     _(HasClass)                                                             \
+    _(GuardToClass)                                                         \
     _(CopySign)                                                             \
     _(Rotate)                                                               \
     _(NewDerivedTypedObject)                                                \
diff --git a/js/src/jit/MacroAssembler.cpp b/js/src/jit/MacroAssembler.cpp
index f633b9b7b..9dbbe7624 100644
--- a/js/src/jit/MacroAssembler.cpp
+++ b/js/src/jit/MacroAssembler.cpp
@@ -2214,6 +2214,12 @@ MacroAssembler::finish()
     }
 
     MacroAssemblerSpecific::finish();
+
+    MOZ_RELEASE_ASSERT(size() <= MaxCodeBytesPerProcess,
+                       "AssemblerBuffer should ensure we don't exceed MaxCodeBytesPerProcess");
+
+    if (bytesNeeded() > MaxCodeBytesPerProcess)
+        setOOM();
 }
 
 void
diff --git a/js/src/jit/ProcessExecutableMemory.cpp b/js/src/jit/ProcessExecutableMemory.cpp
index 71c2ab0dc..301541541 100644
--- a/js/src/jit/ProcessExecutableMemory.cpp
+++ b/js/src/jit/ProcessExecutableMemory.cpp
@@ -385,14 +385,6 @@ class PageBitSet
 #endif
 };
 
-// Limit on the number of bytes of executable memory to prevent JIT spraying
-// attacks.
-#if JS_BITS_PER_WORD == 32
-static const size_t MaxCodeBytesPerProcess = 128 * 1024 * 1024;
-#else
-static const size_t MaxCodeBytesPerProcess = 1 * 1024 * 1024 * 1024;
-#endif
-
 // Per-process executable memory allocator. It reserves a block of memory of
 // MaxCodeBytesPerProcess bytes, then allocates/deallocates pages from that.
 //
diff --git a/js/src/jit/ProcessExecutableMemory.h b/js/src/jit/ProcessExecutableMemory.h
index 078ce7cb7..a0e2fab98 100644
--- a/js/src/jit/ProcessExecutableMemory.h
+++ b/js/src/jit/ProcessExecutableMemory.h
@@ -17,6 +17,14 @@ namespace jit {
 // alignment though.
 static const size_t ExecutableCodePageSize = 64 * 1024;
 
+// Limit on the number of bytes of executable memory to prevent JIT spraying
+// attacks.
+#if JS_BITS_PER_WORD == 32
+static const size_t MaxCodeBytesPerProcess = 128 * 1024 * 1024;
+#else
+static const size_t MaxCodeBytesPerProcess = 1 * 1024 * 1024 * 1024;
+#endif
+
 enum class ProtectionSetting {
     Protected, // Not readable, writable, or executable.
     Writable,
diff --git a/js/src/jit/RegisterSets.h b/js/src/jit/RegisterSets.h
index 0a4045dd7..08ae53f16 100644
--- a/js/src/jit/RegisterSets.h
+++ b/js/src/jit/RegisterSets.h
@@ -226,13 +226,13 @@ class ConstantOrRegister
 
     // Space to hold either a Value or a TypedOrValueRegister.
     union U {
-        Value constant;
+        JS::UninitializedValue constant;
         TypedOrValueRegister reg;
     } data;
 
-    const Value& dataValue() const {
+    Value dataValue() const {
         MOZ_ASSERT(constant());
-        return data.constant;
+        return data.constant.asValueRef();
     }
     void setDataValue(const Value& value) {
         MOZ_ASSERT(constant());
@@ -268,7 +268,7 @@ class ConstantOrRegister
         return constant_;
     }
 
-    const Value& value() const {
+    Value value() const {
         return dataValue();
     }
 
diff --git a/js/src/jit/RematerializedFrame.cpp b/js/src/jit/RematerializedFrame.cpp
index cb324220c..32fad1267 100644
--- a/js/src/jit/RematerializedFrame.cpp
+++ b/js/src/jit/RematerializedFrame.cpp
@@ -61,9 +61,17 @@ RematerializedFrame::New(JSContext* cx, uint8_t* top, InlineFrameIterator& iter,
 {
     unsigned numFormals = iter.isFunctionFrame() ? iter.calleeTemplate()->nargs() : 0;
     unsigned argSlots = Max(numFormals, iter.numActualArgs());
-    size_t numBytes = sizeof(RematerializedFrame) +
-        (argSlots + iter.script()->nfixed()) * sizeof(Value) -
-        sizeof(Value); // 1 Value included in sizeof(RematerializedFrame)
+    unsigned extraSlots = argSlots + iter.script()->nfixed();
+
+    // One Value slot is included in sizeof(RematerializedFrame), so we can
+    // reduce the extra slot count by one.  However, if there are zero slot
+    // allocations total, then reducing the slots by one will lead to
+    // the memory allocation being smaller  than sizeof(RematerializedFrame).
+    if (extraSlots > 0)
+        extraSlots -= 1;
+
+    size_t numBytes = sizeof(RematerializedFrame) + (extraSlots * sizeof(Value));
+    MOZ_ASSERT(numBytes >= sizeof(RematerializedFrame));
 
     void* buf = cx->pod_calloc<uint8_t>(numBytes);
     if (!buf)
diff --git a/js/src/jit/shared/IonAssemblerBuffer.h b/js/src/jit/shared/IonAssemblerBuffer.h
index cc20e26d2..3a6552696 100644
--- a/js/src/jit/shared/IonAssemblerBuffer.h
+++ b/js/src/jit/shared/IonAssemblerBuffer.h
@@ -181,6 +181,10 @@ class AssemblerBuffer
 
   protected:
     virtual Slice* newSlice(LifoAlloc& a) {
+        if (size() > MaxCodeBytesPerProcess - sizeof(Slice)) {
+            fail_oom();
+            return nullptr;
+        }
         Slice* tmp = static_cast<Slice*>(a.alloc(sizeof(Slice)));
         if (!tmp) {
             fail_oom();
diff --git a/js/src/jit/shared/LIR-shared.h b/js/src/jit/shared/LIR-shared.h
index 9dcb527c5..f4adcc63c 100644
--- a/js/src/jit/shared/LIR-shared.h
+++ b/js/src/jit/shared/LIR-shared.h
@@ -7867,6 +7867,29 @@ class LHasClass : public LInstructionHelper<1, 1, 0>
     }
 };
 
+class LGuardToClass : public LInstructionHelper<1, 1, 1>
+{
+  public:
+    LIR_HEADER(GuardToClass);
+    explicit LGuardToClass(const LAllocation& lhs, const LDefinition& temp)
+    {
+        setOperand(0, lhs);
+        setTemp(0, temp);
+    }
+
+    const LAllocation* lhs() {
+        return getOperand(0);
+    }
+
+    const LDefinition* temp() {
+        return getTemp(0);
+    }
+
+    MGuardToClass* mir() const {
+        return mir_->toGuardToClass();
+    }
+};
+
 template<size_t Defs, size_t Ops>
 class LWasmSelectBase : public LInstructionHelper<Defs, Ops, 0>
 {
diff --git a/js/src/jit/shared/LOpcodes-shared.h b/js/src/jit/shared/LOpcodes-shared.h
index 3eea1b449..fe2ab5ea3 100644
--- a/js/src/jit/shared/LOpcodes-shared.h
+++ b/js/src/jit/shared/LOpcodes-shared.h
@@ -386,6 +386,7 @@
     _(IsObject)                     \
     _(IsObjectAndBranch)            \
     _(HasClass)                     \
+    _(GuardToClass)                 \
     _(RecompileCheck)               \
     _(MemoryBarrier)                \
     _(AssertRangeI)                 \
diff --git a/js/src/jit/x86-shared/AssemblerBuffer-x86-shared.h b/js/src/jit/x86-shared/AssemblerBuffer-x86-shared.h
index 8cb557784..fe678fc7d 100644
--- a/js/src/jit/x86-shared/AssemblerBuffer-x86-shared.h
+++ b/js/src/jit/x86-shared/AssemblerBuffer-x86-shared.h
@@ -68,6 +68,33 @@ namespace js {
 
 namespace jit {
 
+    // AllocPolicy for AssemblerBuffer. OOMs when trying to allocate more than
+    // MaxCodeBytesPerProcess bytes. Use private inheritance to make sure we
+    // explicitly have to expose SystemAllocPolicy methods.
+    class AssemblerBufferAllocPolicy : private SystemAllocPolicy
+    {
+      public:
+        using SystemAllocPolicy::checkSimulatedOOM;
+        using SystemAllocPolicy::reportAllocOverflow;
+        using SystemAllocPolicy::free_;
+
+        template <typename T> T* pod_realloc(T* p, size_t oldSize, size_t newSize) {
+            static_assert(sizeof(T) == 1,
+                          "AssemblerBufferAllocPolicy should only be used with byte vectors");
+            MOZ_ASSERT(oldSize <= MaxCodeBytesPerProcess);
+            if (MOZ_UNLIKELY(newSize > MaxCodeBytesPerProcess))
+                return nullptr;
+            return SystemAllocPolicy::pod_realloc<T>(p, oldSize, newSize);
+        }
+        template <typename T> T* pod_malloc(size_t numElems) {
+            static_assert(sizeof(T) == 1,
+                          "AssemblerBufferAllocPolicy should only be used with byte vectors");
+            if (MOZ_UNLIKELY(numElems > MaxCodeBytesPerProcess))
+                return nullptr;
+            return SystemAllocPolicy::pod_malloc<T>(numElems);
+        }
+    };
+
     class AssemblerBuffer
     {
         template<size_t size, typename T>
@@ -93,6 +120,9 @@ namespace jit {
 
         void ensureSpace(size_t space)
         {
+            // This should only be called with small |space| values to ensure
+            // we don't overflow below.
+            MOZ_ASSERT(space <= 16);
             if (MOZ_UNLIKELY(!m_buffer.reserve(m_buffer.length() + space)))
                 oomDetected();
         }
@@ -168,7 +198,7 @@ namespace jit {
             m_buffer.clear();
         }
 
-        PageProtectingVector<unsigned char, 256, SystemAllocPolicy> m_buffer;
+        PageProtectingVector<unsigned char, 256, AssemblerBufferAllocPolicy> m_buffer;
         bool m_oom;
     };
 
diff --git a/js/src/js.msg b/js/src/js.msg
index 8d492f523..a276dab94 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -474,6 +474,8 @@ MSG_DEF(JSMSG_INTL_OBJECT_NOT_INITED,  3, JSEXN_TYPEERR, "Intl.{0}.prototype.{1}
 MSG_DEF(JSMSG_INTL_OBJECT_REINITED,    0, JSEXN_TYPEERR, "can't initialize object twice as an object of an Intl constructor")
 MSG_DEF(JSMSG_INVALID_CURRENCY_CODE,   1, JSEXN_RANGEERR, "invalid currency code in NumberFormat(): {0}")
 MSG_DEF(JSMSG_INVALID_DIGITS_VALUE,    1, JSEXN_RANGEERR, "invalid digits value: {0}")
+MSG_DEF(JSMSG_INVALID_KEYS_TYPE,       0, JSEXN_TYPEERR, "calendar info keys must be an object or undefined")
+MSG_DEF(JSMSG_INVALID_KEY,             1, JSEXN_RANGEERR, "invalid key: {0}")
 MSG_DEF(JSMSG_INVALID_LANGUAGE_TAG,    1, JSEXN_RANGEERR, "invalid language tag: {0}")
 MSG_DEF(JSMSG_INVALID_LOCALES_ELEMENT, 0, JSEXN_TYPEERR, "invalid element in locales argument")
 MSG_DEF(JSMSG_INVALID_LOCALE_MATCHER,  1, JSEXN_RANGEERR, "invalid locale matcher in supportedLocalesOf(): {0}")
diff --git a/js/src/jsapi-tests/moz.build b/js/src/jsapi-tests/moz.build
index f7a6080aa..277a145b0 100644
--- a/js/src/jsapi-tests/moz.build
+++ b/js/src/jsapi-tests/moz.build
@@ -135,7 +135,7 @@ LOCAL_INCLUDES += [
     '..',
 ]
 
-if CONFIG['ENABLE_INTL_API'] and CONFIG['MOZ_ICU_DATA_ARCHIVE']:
+if CONFIG['MOZ_ICU_DATA_ARCHIVE']:
     # The ICU libraries linked into libmozjs will not include the ICU data,
     # so link it directly.
     USE_LIBS += ['icudata']
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 989abe47c..c1195cc00 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -5222,7 +5222,7 @@ JS_ResetDefaultLocale(JSContext* cx);
 struct JSLocaleCallbacks {
     JSLocaleToUpperCase     localeToUpperCase;
     JSLocaleToLowerCase     localeToLowerCase;
-    JSLocaleCompare         localeCompare; // not used #if EXPOSE_INTL_API
+    JSLocaleCompare         localeCompare; // not used
     JSLocaleToUnicode       localeToUnicode;
 };
 
diff --git a/js/src/jsdate.cpp b/js/src/jsdate.cpp
index ccaeda2a3..52294a5df 100755
--- a/js/src/jsdate.cpp
+++ b/js/src/jsdate.cpp
@@ -354,10 +354,22 @@ MakeDate(double day, double time)
 JS_PUBLIC_API(double)
 JS::MakeDate(double year, unsigned month, unsigned day)
 {
+    MOZ_ASSERT(month <= 11);
+    MOZ_ASSERT(day >= 1 && day <= 31);
+
     return ::MakeDate(MakeDay(year, month, day), 0);
 }
 
 JS_PUBLIC_API(double)
+JS::MakeDate(double year, unsigned month, unsigned day, double time)
+{
+    MOZ_ASSERT(month <= 11);
+    MOZ_ASSERT(day >= 1 && day <= 31);
+
+    return ::MakeDate(MakeDay(year, month, day), time);
+}
+
+JS_PUBLIC_API(double)
 JS::YearFromTime(double time)
 {
     return ::YearFromTime(time);
@@ -2731,77 +2743,6 @@ ToLocaleFormatHelper(JSContext* cx, HandleObject obj, const char* format, Mutabl
     return true;
 }
 
-#if !EXPOSE_INTL_API
-/* ES5 15.9.5.5. */
-MOZ_ALWAYS_INLINE bool
-date_toLocaleString_impl(JSContext* cx, const CallArgs& args)
-{
-    /*
-     * Use '%#c' for windows, because '%c' is backward-compatible and non-y2k
-     * with msvc; '%#c' requests that a full year be used in the result string.
-     */
-    static const char format[] =
-#if defined(_WIN32) && !defined(__MWERKS__)
-                                   "%#c"
-#else
-                                   "%c"
-#endif
-                                   ;
-
-    Rooted<DateObject*> dateObj(cx, &args.thisv().toObject().as<DateObject>());
-    return ToLocaleFormatHelper(cx, dateObj, format, args.rval());
-}
-
-static bool
-date_toLocaleString(JSContext* cx, unsigned argc, Value* vp)
-{
-    CallArgs args = CallArgsFromVp(argc, vp);
-    return CallNonGenericMethod<IsDate, date_toLocaleString_impl>(cx, args);
-}
-
-/* ES5 15.9.5.6. */
-MOZ_ALWAYS_INLINE bool
-date_toLocaleDateString_impl(JSContext* cx, const CallArgs& args)
-{
-    /*
-     * Use '%#x' for windows, because '%x' is backward-compatible and non-y2k
-     * with msvc; '%#x' requests that a full year be used in the result string.
-     */
-    static const char format[] =
-#if defined(_WIN32) && !defined(__MWERKS__)
-                                   "%#x"
-#else
-                                   "%x"
-#endif
-                                   ;
-
-    Rooted<DateObject*> dateObj(cx, &args.thisv().toObject().as<DateObject>());
-    return ToLocaleFormatHelper(cx, dateObj, format, args.rval());
-}
-
-static bool
-date_toLocaleDateString(JSContext* cx, unsigned argc, Value* vp)
-{
-    CallArgs args = CallArgsFromVp(argc, vp);
-    return CallNonGenericMethod<IsDate, date_toLocaleDateString_impl>(cx, args);
-}
-
-/* ES5 15.9.5.7. */
-MOZ_ALWAYS_INLINE bool
-date_toLocaleTimeString_impl(JSContext* cx, const CallArgs& args)
-{
-    Rooted<DateObject*> dateObj(cx, &args.thisv().toObject().as<DateObject>());
-    return ToLocaleFormatHelper(cx, dateObj, "%X", args.rval());
-}
-
-static bool
-date_toLocaleTimeString(JSContext* cx, unsigned argc, Value* vp)
-{
-    CallArgs args = CallArgsFromVp(argc, vp);
-    return CallNonGenericMethod<IsDate, date_toLocaleTimeString_impl>(cx, args);
-}
-#endif /* !EXPOSE_INTL_API */
-
 MOZ_ALWAYS_INLINE bool
 date_toLocaleFormat_impl(JSContext* cx, const CallArgs& args)
 {
@@ -3025,15 +2966,9 @@ static const JSFunctionSpec date_methods[] = {
     JS_FN("setUTCMilliseconds",  date_setUTCMilliseconds, 1,0),
     JS_FN("toUTCString",         date_toGMTString,        0,0),
     JS_FN("toLocaleFormat",      date_toLocaleFormat,     0,0),
-#if EXPOSE_INTL_API
     JS_SELF_HOSTED_FN(js_toLocaleString_str, "Date_toLocaleString", 0,0),
     JS_SELF_HOSTED_FN("toLocaleDateString", "Date_toLocaleDateString", 0,0),
     JS_SELF_HOSTED_FN("toLocaleTimeString", "Date_toLocaleTimeString", 0,0),
-#else
-    JS_FN(js_toLocaleString_str, date_toLocaleString,     0,0),
-    JS_FN("toLocaleDateString",  date_toLocaleDateString, 0,0),
-    JS_FN("toLocaleTimeString",  date_toLocaleTimeString, 0,0),
-#endif
     JS_FN("toDateString",        date_toDateString,       0,0),
     JS_FN("toTimeString",        date_toTimeString,       0,0),
     JS_FN("toISOString",         date_toISOString,        0,0),
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index 45301dac8..3d4dae9bb 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -2156,7 +2156,7 @@ ArenasToUpdate::getArenasToUpdate(AutoLockHelperThreadState& lock, unsigned maxL
     return { begin, last->next };
 }
 
-struct UpdatePointersTask : public GCParallelTask
+struct UpdatePointersTask : public GCParallelTaskHelper<UpdatePointersTask>
 {
     // Maximum number of arenas to update in one block.
 #ifdef DEBUG
@@ -2172,14 +2172,13 @@ struct UpdatePointersTask : public GCParallelTask
         arenas_.end = nullptr;
     }
 
-    ~UpdatePointersTask() override { join(); }
+    void run();
 
   private:
     JSRuntime* rt_;
     ArenasToUpdate* source_;
     ArenaListSegment arenas_;
 
-    virtual void run() override;
     bool getArenasToUpdate();
     void updateArenas();
 };
@@ -2276,7 +2275,7 @@ GCRuntime::updateCellPointers(MovingTracer* trc, Zone* zone, AllocKinds kinds, s
         for (size_t i = 0; i < bgTaskCount && !bgArenas.done(); i++) {
             bgTasks[i].emplace(rt, &bgArenas, lock);
             startTask(*bgTasks[i], gcstats::PHASE_COMPACT_UPDATE_CELLS, lock);
-            tasksStarted = i;
+            tasksStarted++;
         }
     }
 
@@ -2985,7 +2984,6 @@ js::gc::BackgroundDecommitTask::run()
     AutoLockGC lock(runtime);
 
     for (Chunk* chunk : toDecommit) {
-
         // The arena list is not doubly-linked, so we have to work in the free
         // list order and not in the natural order.
         while (chunk->info.numArenasFreeCommitted) {
@@ -4359,7 +4357,8 @@ GCRuntime::endMarkingZoneGroup()
     marker.setMarkColorBlack();
 }
 
-class GCSweepTask : public GCParallelTask
+template <typename Derived>
+class GCSweepTask : public GCParallelTaskHelper<Derived>
 {
     GCSweepTask(const GCSweepTask&) = delete;
 
@@ -4369,13 +4368,13 @@ class GCSweepTask : public GCParallelTask
   public:
     explicit GCSweepTask(JSRuntime* rt) : runtime(rt) {}
     GCSweepTask(GCSweepTask&& other)
-      : GCParallelTask(mozilla::Move(other)),
+      : GCParallelTaskHelper<Derived>(mozilla::Move(other)),
         runtime(other.runtime)
     {}
 };
 
 // Causes the given WeakCache to be swept when run.
-class SweepWeakCacheTask : public GCSweepTask
+class SweepWeakCacheTask : public GCSweepTask<SweepWeakCacheTask>
 {
     JS::WeakCache<void*>& cache;
 
@@ -4387,15 +4386,15 @@ class SweepWeakCacheTask : public GCSweepTask
       : GCSweepTask(mozilla::Move(other)), cache(other.cache)
     {}
 
-    void run() override {
+    void run() {
         cache.sweep();
     }
 };
 
 #define MAKE_GC_SWEEP_TASK(name)                                              \
-    class name : public GCSweepTask {                                         \
-        void run() override;                                                  \
+    class name : public GCSweepTask<name> {                                   \
       public:                                                                 \
+        void run();                                                           \
         explicit name (JSRuntime* rt) : GCSweepTask(rt) {}                    \
     }
 MAKE_GC_SWEEP_TASK(SweepAtomsTask);
@@ -4447,7 +4446,8 @@ SweepMiscTask::run()
 }
 
 void
-GCRuntime::startTask(GCParallelTask& task, gcstats::Phase phase, AutoLockHelperThreadState& locked)
+GCRuntime::startTask(GCParallelTask& task, gcstats::Phase phase,
+                     AutoLockHelperThreadState& locked)
 {
     if (!task.startWithLockHeld(locked)) {
         AutoUnlockHelperThreadState unlock(locked);
@@ -4457,7 +4457,8 @@ GCRuntime::startTask(GCParallelTask& task, gcstats::Phase phase, AutoLockHelperT
 }
 
 void
-GCRuntime::joinTask(GCParallelTask& task, gcstats::Phase phase, AutoLockHelperThreadState& locked)
+GCRuntime::joinTask(GCParallelTask& task, gcstats::Phase phase,
+                    AutoLockHelperThreadState& locked)
 {
     gcstats::AutoPhase ap(stats, task, phase);
     task.joinWithLockHeld(locked);
diff --git a/js/src/jsgc.h b/js/src/jsgc.h
index 7ad176d84..d3cf31fe7 100644
--- a/js/src/jsgc.h
+++ b/js/src/jsgc.h
@@ -12,6 +12,7 @@
 #include "mozilla/Atomics.h"
 #include "mozilla/EnumeratedArray.h"
 #include "mozilla/MemoryReporting.h"
+#include "mozilla/Move.h"
 #include "mozilla/TypeTraits.h"
 
 #include "js/GCAPI.h"
@@ -936,10 +937,19 @@ class GCHelperState
 };
 
 // A generic task used to dispatch work to the helper thread system.
-// Users should derive from GCParallelTask add what data they need and
-// override |run|.
+// Users supply a function pointer to call.
+//
+// Note that we don't use virtual functions here because destructors can write
+// the vtable pointer on entry, which can causes races if synchronization
+// happens there.
 class GCParallelTask
 {
+  public:
+    using TaskFunc = void (*)(GCParallelTask*);
+
+  private:
+    TaskFunc func_;
+
     // The state of the parallel computation.
     enum TaskState {
         NotStarted,
@@ -956,19 +966,24 @@ class GCParallelTask
     // A flag to signal a request for early completion of the off-thread task.
     mozilla::Atomic<bool> cancel_;
 
-    virtual void run() = 0;
-
   public:
-    GCParallelTask() : state(NotStarted), duration_(0) {}
+    explicit GCParallelTask(TaskFunc func)
+      : func_(func),
+        state(NotStarted),
+        duration_(0),
+        cancel_(false)
+    {}
+
     GCParallelTask(GCParallelTask&& other)
-      : state(other.state),
+      : func_(other.func_),
+        state(other.state),
         duration_(0),
         cancel_(false)
     {}
 
     // Derived classes must override this to ensure that join() gets called
     // before members get destructed.
-    virtual ~GCParallelTask();
+    ~GCParallelTask();
 
     // Time spent in the most recent invocation of this task.
     int64_t duration() const { return duration_; }
@@ -997,12 +1012,34 @@ class GCParallelTask
     bool isRunningWithLockHeld(const AutoLockHelperThreadState& locked) const;
     bool isRunning() const;
 
+    void runTask() {
+        func_(this);
+    }
+
     // This should be friended to HelperThread, but cannot be because it
     // would introduce several circular dependencies.
   public:
     void runFromHelperThread(AutoLockHelperThreadState& locked);
 };
 
+// CRTP template to handle cast to derived type when calling run().
+template <typename Derived>
+class GCParallelTaskHelper : public GCParallelTask
+{
+  public:
+    GCParallelTaskHelper()
+      : GCParallelTask(&runTaskTyped)
+    {}
+    GCParallelTaskHelper(GCParallelTaskHelper&& other)
+      : GCParallelTask(mozilla::Move(other))
+    {}
+
+  private:
+    static void runTaskTyped(GCParallelTask* task) {
+        static_cast<Derived*>(task)->run();
+    }
+};
+
 typedef void (*IterateChunkCallback)(JSRuntime* rt, void* data, gc::Chunk* chunk);
 typedef void (*IterateZoneCallback)(JSRuntime* rt, void* data, JS::Zone* zone);
 typedef void (*IterateArenaCallback)(JSRuntime* rt, void* data, gc::Arena* arena,
diff --git a/js/src/jsnativestack.cpp b/js/src/jsnativestack.cpp
index 05928ea3d..166a5a4f7 100644
--- a/js/src/jsnativestack.cpp
+++ b/js/src/jsnativestack.cpp
@@ -21,6 +21,18 @@
 #  include <unistd.h>
 # endif
 
+# if defined(XP_LINUX) && !defined(ANDROID) && defined(__GLIBC__)
+#  include <dlfcn.h>
+#  include <sys/syscall.h>
+#  include <sys/types.h>
+#  include <unistd.h>
+static pid_t
+gettid()
+{
+    return syscall(__NR_gettid);
+}
+# endif
+
 #else
 # error "Unsupported platform"
 
@@ -88,6 +100,52 @@ js::GetNativeStackBaseImpl()
         context.uc_stack.ss_size;
 }
 
+#elif defined(XP_LINUX) && !defined(ANDROID) && defined(__GLIBC__)
+void*
+js::GetNativeStackBaseImpl()
+{
+    // On the main thread, get stack base from glibc's __libc_stack_end rather than pthread APIs
+    // to avoid filesystem calls /proc/self/maps.  Non-main threads spawned with pthreads can read
+    // this information directly from their pthread struct, but when using the pthreads API, the
+    // main thread must go parse /proc/self/maps to figure the mapped stack address space ranges.
+    // We want to avoid reading from /proc/ so that the application can run in restricted
+    // environments where /proc may not be mounted (e.g. chroot).
+    if (gettid() == getpid()) {
+        void** pLibcStackEnd = (void**)dlsym(RTLD_DEFAULT, "__libc_stack_end");
+
+        // If __libc_stack_end is not found, architecture specific frame pointer hopping will need
+        // to be implemented.
+        MOZ_RELEASE_ASSERT(pLibcStackEnd, "__libc_stack_end unavailable, unable to setup stack range for JS.");
+        void* stackBase = *pLibcStackEnd;
+        MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS.");
+
+        // We don't need to fix stackBase, as it already roughly points to beginning of the stack.
+        return stackBase;
+    }
+
+    // Non-main threads have the required info stored in memory, so no filesystem calls are made.
+    pthread_t thread = pthread_self();
+    pthread_attr_t sattr;
+    pthread_attr_init(&sattr);
+    pthread_getattr_np(thread, &sattr);
+
+    // stackBase will be the *lowest* address on all architectures.
+    void* stackBase = nullptr;
+    size_t stackSize = 0;
+    int rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
+    if (rc) {
+        MOZ_CRASH("Call to pthread_attr_getstack failed, unable to setup stack range for JS.");
+    }
+    MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS.");
+    pthread_attr_destroy(&sattr);
+
+# if JS_STACK_GROWTH_DIRECTION > 0
+    return stackBase;
+# else
+    return static_cast<char*>(stackBase) + stackSize;
+# endif
+}
+
 #else /* XP_UNIX */
 
 void*
@@ -156,11 +214,15 @@ js::GetNativeStackBaseImpl()
         // the truth.
         rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
 # else
+    // Use the default pthread_attr_getstack() call. Note that this function
+    // differs between libc implementations and could imply /proc access etc.
+    // which may not work in restricted environments.
     rc = pthread_attr_getstack(&sattr, &stackBase, &stackSize);
 # endif
-    if (rc)
-        MOZ_CRASH();
-    MOZ_ASSERT(stackBase);
+    if (rc) {
+        MOZ_CRASH("Call to pthread_attr_getstack failed, unable to setup stack range for JS.");
+    }
+    MOZ_RELEASE_ASSERT(stackBase, "Invalid stack base, unable to setup stack range for JS.");
     pthread_attr_destroy(&sattr);
 
 #  if JS_STACK_GROWTH_DIRECTION > 0
diff --git a/js/src/jsnum.cpp b/js/src/jsnum.cpp
index 8885737f7..28ed15159 100644
--- a/js/src/jsnum.cpp
+++ b/js/src/jsnum.cpp
@@ -724,141 +724,6 @@ js::num_toString(JSContext* cx, unsigned argc, Value* vp)
     return CallNonGenericMethod<IsNumber, num_toString_impl>(cx, args);
 }
 
-#if !EXPOSE_INTL_API
-MOZ_ALWAYS_INLINE bool
-num_toLocaleString_impl(JSContext* cx, const CallArgs& args)
-{
-    MOZ_ASSERT(IsNumber(args.thisv()));
-
-    double d = Extract(args.thisv());
-
-    RootedString str(cx, NumberToStringWithBase<CanGC>(cx, d, 10));
-    if (!str) {
-        JS_ReportOutOfMemory(cx);
-        return false;
-    }
-
-    /*
-     * Create the string, move back to bytes to make string twiddling
-     * a bit easier and so we can insert platform charset seperators.
-     */
-    JSAutoByteString numBytes(cx, str);
-    if (!numBytes)
-        return false;
-    const char* num = numBytes.ptr();
-    if (!num)
-        return false;
-
-    /*
-     * Find the first non-integer value, whether it be a letter as in
-     * 'Infinity', a decimal point, or an 'e' from exponential notation.
-     */
-    const char* nint = num;
-    if (*nint == '-')
-        nint++;
-    while (*nint >= '0' && *nint <= '9')
-        nint++;
-    int digits = nint - num;
-    const char* end = num + digits;
-    if (!digits) {
-        args.rval().setString(str);
-        return true;
-    }
-
-    JSRuntime* rt = cx->runtime();
-    size_t thousandsLength = strlen(rt->thousandsSeparator);
-    size_t decimalLength = strlen(rt->decimalSeparator);
-
-    /* Figure out how long resulting string will be. */
-    int buflen = strlen(num);
-    if (*nint == '.')
-        buflen += decimalLength - 1; /* -1 to account for existing '.' */
-
-    const char* numGrouping;
-    const char* tmpGroup;
-    numGrouping = tmpGroup = rt->numGrouping;
-    int remainder = digits;
-    if (*num == '-')
-        remainder--;
-
-    while (*tmpGroup != CHAR_MAX && *tmpGroup != '\0') {
-        if (*tmpGroup >= remainder)
-            break;
-        buflen += thousandsLength;
-        remainder -= *tmpGroup;
-        tmpGroup++;
-    }
-
-    int nrepeat;
-    if (*tmpGroup == '\0' && *numGrouping != '\0') {
-        nrepeat = (remainder - 1) / tmpGroup[-1];
-        buflen += thousandsLength * nrepeat;
-        remainder -= nrepeat * tmpGroup[-1];
-    } else {
-        nrepeat = 0;
-    }
-    tmpGroup--;
-
-    char* buf = cx->pod_malloc<char>(buflen + 1);
-    if (!buf)
-        return false;
-
-    char* tmpDest = buf;
-    const char* tmpSrc = num;
-
-    while (*tmpSrc == '-' || remainder--) {
-        MOZ_ASSERT(tmpDest - buf < buflen);
-        *tmpDest++ = *tmpSrc++;
-    }
-    while (tmpSrc < end) {
-        MOZ_ASSERT(tmpDest - buf + ptrdiff_t(thousandsLength) <= buflen);
-        strcpy(tmpDest, rt->thousandsSeparator);
-        tmpDest += thousandsLength;
-        MOZ_ASSERT(tmpDest - buf + *tmpGroup <= buflen);
-        js_memcpy(tmpDest, tmpSrc, *tmpGroup);
-        tmpDest += *tmpGroup;
-        tmpSrc += *tmpGroup;
-        if (--nrepeat < 0)
-            tmpGroup--;
-    }
-
-    if (*nint == '.') {
-        MOZ_ASSERT(tmpDest - buf + ptrdiff_t(decimalLength) <= buflen);
-        strcpy(tmpDest, rt->decimalSeparator);
-        tmpDest += decimalLength;
-        MOZ_ASSERT(tmpDest - buf + ptrdiff_t(strlen(nint + 1)) <= buflen);
-        strcpy(tmpDest, nint + 1);
-    } else {
-        MOZ_ASSERT(tmpDest - buf + ptrdiff_t(strlen(nint)) <= buflen);
-        strcpy(tmpDest, nint);
-    }
-
-    if (cx->runtime()->localeCallbacks && cx->runtime()->localeCallbacks->localeToUnicode) {
-        Rooted<Value> v(cx, StringValue(str));
-        bool ok = !!cx->runtime()->localeCallbacks->localeToUnicode(cx, buf, &v);
-        if (ok)
-            args.rval().set(v);
-        js_free(buf);
-        return ok;
-    }
-
-    str = NewStringCopyN<CanGC>(cx, buf, buflen);
-    js_free(buf);
-    if (!str)
-        return false;
-
-    args.rval().setString(str);
-    return true;
-}
-
-static bool
-num_toLocaleString(JSContext* cx, unsigned argc, Value* vp)
-{
-    CallArgs args = CallArgsFromVp(argc, vp);
-    return CallNonGenericMethod<IsNumber, num_toLocaleString_impl>(cx, args);
-}
-#endif /* !EXPOSE_INTL_API */
-
 MOZ_ALWAYS_INLINE bool
 num_valueOf_impl(JSContext* cx, const CallArgs& args)
 {
@@ -1075,11 +940,7 @@ static const JSFunctionSpec number_methods[] = {
     JS_FN(js_toSource_str,       num_toSource,          0, 0),
 #endif
     JS_FN(js_toString_str,       num_toString,          1, 0),
-#if EXPOSE_INTL_API
     JS_SELF_HOSTED_FN(js_toLocaleString_str, "Number_toLocaleString", 0,0),
-#else
-    JS_FN(js_toLocaleString_str, num_toLocaleString,     0,0),
-#endif
     JS_FN(js_valueOf_str,        num_valueOf,           0, 0),
     JS_FN("toFixed",             num_toFixed,           1, 0),
     JS_FN("toExponential",       num_toExponential,     1, 0),
@@ -1130,76 +991,11 @@ js::FIX_FPU()
 #endif
 }
 
-bool
+void
 js::InitRuntimeNumberState(JSRuntime* rt)
 {
     FIX_FPU();
-
-    // XXX If EXPOSE_INTL_API becomes true all the time at some point,
-    //     js::InitRuntimeNumberState is no longer fallible, and we should
-    //     change its return type.
-#if !EXPOSE_INTL_API
-    /* Copy locale-specific separators into the runtime strings. */
-    const char* thousandsSeparator;
-    const char* decimalPoint;
-    const char* grouping;
-#ifdef HAVE_LOCALECONV
-    struct lconv* locale = localeconv();
-    thousandsSeparator = locale->thousands_sep;
-    decimalPoint = locale->decimal_point;
-    grouping = locale->grouping;
-#else
-    thousandsSeparator = getenv("LOCALE_THOUSANDS_SEP");
-    decimalPoint = getenv("LOCALE_DECIMAL_POINT");
-    grouping = getenv("LOCALE_GROUPING");
-#endif
-    if (!thousandsSeparator)
-        thousandsSeparator = "'";
-    if (!decimalPoint)
-        decimalPoint = ".";
-    if (!grouping)
-        grouping = "\3\0";
-
-    /*
-     * We use single malloc to get the memory for all separator and grouping
-     * strings.
-     */
-    size_t thousandsSeparatorSize = strlen(thousandsSeparator) + 1;
-    size_t decimalPointSize = strlen(decimalPoint) + 1;
-    size_t groupingSize = strlen(grouping) + 1;
-
-    char* storage = js_pod_malloc<char>(thousandsSeparatorSize +
-                                        decimalPointSize +
-                                        groupingSize);
-    if (!storage)
-        return false;
-
-    js_memcpy(storage, thousandsSeparator, thousandsSeparatorSize);
-    rt->thousandsSeparator = storage;
-    storage += thousandsSeparatorSize;
-
-    js_memcpy(storage, decimalPoint, decimalPointSize);
-    rt->decimalSeparator = storage;
-    storage += decimalPointSize;
-
-    js_memcpy(storage, grouping, groupingSize);
-    rt->numGrouping = grouping;
-#endif /* !EXPOSE_INTL_API */
-    return true;
-}
-
-#if !EXPOSE_INTL_API
-void
-js::FinishRuntimeNumberState(JSRuntime* rt)
-{
-    /*
-     * The free also releases the memory for decimalSeparator and numGrouping
-     * strings.
-     */
-    char* storage = const_cast<char*>(rt->thousandsSeparator);
-    js_free(storage);
 }
-#endif
 
 JSObject*
 js::InitNumberClass(JSContext* cx, HandleObject obj)
diff --git a/js/src/jsnum.h b/js/src/jsnum.h
index 62b3d617f..8dff45f69 100644
--- a/js/src/jsnum.h
+++ b/js/src/jsnum.h
@@ -34,13 +34,7 @@ namespace js {
 
 class StringBuffer;
 
-extern MOZ_MUST_USE bool
-InitRuntimeNumberState(JSRuntime* rt);
-
-#if !EXPOSE_INTL_API
-extern void
-FinishRuntimeNumberState(JSRuntime* rt);
-#endif
+void InitRuntimeNumberState(JSRuntime* rt);
 
 /* Initialize the Number class, returning its prototype object. */
 extern JSObject*
diff --git a/js/src/jsprototypes.h b/js/src/jsprototypes.h
index f409dce95..dc7cdb85a 100644
--- a/js/src/jsprototypes.h
+++ b/js/src/jsprototypes.h
@@ -37,11 +37,7 @@
 #define TYPED_ARRAY_CLASP(type)     (&TypedArrayObject::classes[Scalar::type])
 #define ERROR_CLASP(type)           (&ErrorObject::classes[type])
 
-#ifdef EXPOSE_INTL_API
 #define IF_INTL(real,imaginary) real
-#else
-#define IF_INTL(real,imaginary) imaginary
-#endif
 
 #ifdef ENABLE_BINARYDATA
 #define IF_BDATA(real,imaginary) real
diff --git a/js/src/jsstr.cpp b/js/src/jsstr.cpp
index 7adeed620..4151d012b 100644
--- a/js/src/jsstr.cpp
+++ b/js/src/jsstr.cpp
@@ -36,9 +36,7 @@
 #include "jit/InlinableNatives.h"
 #include "js/Conversions.h"
 #include "js/UniquePtr.h"
-#if ENABLE_INTL_API
 #include "unicode/unorm.h"
-#endif
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
 #include "vm/Opcodes.h"
@@ -899,38 +897,6 @@ js::str_toLocaleUpperCase(JSContext* cx, unsigned argc, Value* vp)
     return ToUpperCaseHelper(cx, args);
 }
 
-#if !EXPOSE_INTL_API
-bool
-js::str_localeCompare(JSContext* cx, unsigned argc, Value* vp)
-{
-    CallArgs args = CallArgsFromVp(argc, vp);
-    RootedString str(cx, ToStringForStringFunction(cx, args.thisv()));
-    if (!str)
-        return false;
-
-    RootedString thatStr(cx, ToString<CanGC>(cx, args.get(0)));
-    if (!thatStr)
-        return false;
-
-    if (cx->runtime()->localeCallbacks && cx->runtime()->localeCallbacks->localeCompare) {
-        RootedValue result(cx);
-        if (!cx->runtime()->localeCallbacks->localeCompare(cx, str, thatStr, &result))
-            return false;
-
-        args.rval().set(result);
-        return true;
-    }
-
-    int32_t result;
-    if (!CompareStrings(cx, str, thatStr, &result))
-        return false;
-
-    args.rval().setInt32(result);
-    return true;
-}
-#endif
-
-#if EXPOSE_INTL_API
 /* ES6 20140210 draft 21.1.3.12. */
 bool
 js::str_normalize(JSContext* cx, unsigned argc, Value* vp)
@@ -1007,7 +973,6 @@ js::str_normalize(JSContext* cx, unsigned argc, Value* vp)
     args.rval().setString(ns);
     return true;
 }
-#endif
 
 bool
 js::str_charAt(JSContext* cx, unsigned argc, Value* vp)
@@ -1569,7 +1534,7 @@ RopeMatch(JSContext* cx, JSRope* text, JSLinearString* pat, int* match)
     return true;
 }
 
-/* ES6 draft rc4 21.1.3.7. */
+/* ES6 2015 ST 21.1.3.7 String.prototype.includes */
 bool
 js::str_includes(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -1626,6 +1591,13 @@ js::str_includes(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
+/* ES6 draft <RC4 String.prototype.contains for compatibility */
+bool
+js::str_contains(JSContext* cx, unsigned argc, Value* vp)
+{
+    return js::str_includes(cx, argc, vp);
+}
+
 /* ES6 20120927 draft 15.5.4.7. */
 bool
 js::str_indexOf(JSContext* cx, unsigned argc, Value* vp)
@@ -2590,6 +2562,7 @@ static const JSFunctionSpec string_methods[] = {
     JS_SELF_HOSTED_FN("padEnd", "String_pad_end", 2,0),
     JS_SELF_HOSTED_FN("codePointAt", "String_codePointAt", 1,0),
     JS_FN("includes",          str_includes,          1,0),
+    JS_FN("contains",          str_contains,          1,0),
     JS_FN("indexOf",           str_indexOf,           1,0),
     JS_FN("lastIndexOf",       str_lastIndexOf,       1,0),
     JS_FN("startsWith",        str_startsWith,        1,0),
@@ -2599,15 +2572,9 @@ static const JSFunctionSpec string_methods[] = {
     JS_FN("trimRight",         str_trimRight,         0,0),
     JS_FN("toLocaleLowerCase", str_toLocaleLowerCase, 0,0),
     JS_FN("toLocaleUpperCase", str_toLocaleUpperCase, 0,0),
-#if EXPOSE_INTL_API
     JS_SELF_HOSTED_FN("localeCompare", "String_localeCompare", 1,0),
-#else
-    JS_FN("localeCompare",     str_localeCompare,     1,0),
-#endif
     JS_SELF_HOSTED_FN("repeat", "String_repeat",      1,0),
-#if EXPOSE_INTL_API
     JS_FN("normalize",         str_normalize,         0,0),
-#endif
 
     /* Perl-ish methods (search is actually Python-esque). */
     JS_SELF_HOSTED_FN("match", "String_match",        1,0),
@@ -2918,9 +2885,7 @@ static const JSFunctionSpec string_static_methods[] = {
     JS_SELF_HOSTED_FN("trimRight",       "String_static_trimRight",     1,0),
     JS_SELF_HOSTED_FN("toLocaleLowerCase","String_static_toLocaleLowerCase",1,0),
     JS_SELF_HOSTED_FN("toLocaleUpperCase","String_static_toLocaleUpperCase",1,0),
-#if EXPOSE_INTL_API
     JS_SELF_HOSTED_FN("normalize",       "String_static_normalize",     1,0),
-#endif
     JS_SELF_HOSTED_FN("concat",          "String_static_concat",        2,0),
 
     JS_SELF_HOSTED_FN("localeCompare",   "String_static_localeCompare", 2,0),
diff --git a/js/src/jsstr.h b/js/src/jsstr.h
index 3b92aa21b..118118839 100644
--- a/js/src/jsstr.h
+++ b/js/src/jsstr.h
@@ -9,6 +9,7 @@
 
 #include "mozilla/HashFunctions.h"
 #include "mozilla/PodOperations.h"
+#include "mozilla/TextUtils.h"
 
 #include <stdio.h>
 
@@ -95,7 +96,7 @@ struct JSSubString {
 #define JS7_UNOCT(c)    (JS7_UNDEC(c))
 #define JS7_ISHEX(c)    ((c) < 128 && isxdigit(c))
 #define JS7_UNHEX(c)    (unsigned)(JS7_ISDEC(c) ? (c) - '0' : 10 + tolower(c) - 'a')
-#define JS7_ISLET(c)    ((c) < 128 && isalpha(c))
+#define JS7_ISLET(c)    (mozilla::IsAsciiAlpha(c))
 
 extern size_t
 js_strlen(const char16_t* s);
@@ -377,13 +378,8 @@ str_toLocaleLowerCase(JSContext* cx, unsigned argc, Value* vp);
 extern bool
 str_toLocaleUpperCase(JSContext* cx, unsigned argc, Value* vp);
 
-#if !EXPOSE_INTL_API
-extern bool
-str_localeCompare(JSContext* cx, unsigned argc, Value* vp);
-#else
 extern bool
 str_normalize(JSContext* cx, unsigned argc, Value* vp);
-#endif
 
 extern bool
 str_concat(JSContext* cx, unsigned argc, Value* vp);
diff --git a/js/src/jstypes.h b/js/src/jstypes.h
index 6593d2067..75774e5b8 100644
--- a/js/src/jstypes.h
+++ b/js/src/jstypes.h
@@ -160,10 +160,6 @@
 # if defined(__64BIT__)
 #  define JS_64BIT
 # endif
-#elif defined(__HP_cc) || defined(__HP_aCC)       /* HP-UX cc/aCC */
-# if defined(__LP64__)
-#  define JS_64BIT
-# endif
 #else
 # error "Implement me"
 #endif
diff --git a/js/src/make-source-package.sh b/js/src/make-source-package.sh
index 6e44dd977..e6d3f6df5 100755
--- a/js/src/make-source-package.sh
+++ b/js/src/make-source-package.sh
@@ -151,7 +151,6 @@ case $cmd in
         ${TOPSRCDIR}/memory/moz.build \
         ${TOPSRCDIR}/memory/build \
         ${TOPSRCDIR}/memory/fallible \
-        ${TOPSRCDIR}/memory/jemalloc \
         ${TOPSRCDIR}/memory/mozalloc \
         ${TOPSRCDIR}/memory/mozjemalloc \
         ${tgtpath}/memory
diff --git a/js/src/moz.build b/js/src/moz.build
index a18170a75..a3283b5d6 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -645,18 +645,17 @@ else:
 FORCE_STATIC_LIB = True
 STATIC_LIBRARY_NAME = 'js_static'
 
-if CONFIG['ENABLE_INTL_API']:
-    if not CONFIG['MOZ_ICU_DATA_ARCHIVE']:
-        USE_LIBS += [
-            'icu',
-        ]
-    else:
-        # Linking 'icu' will pull in the stubdata library,
-        # which the shell doesn't want, so link the other bits.
-        USE_LIBS += [
-            'icui18n',
-            'icuuc',
-        ]
+if not CONFIG['MOZ_ICU_DATA_ARCHIVE']:
+    USE_LIBS += [
+        'icu',
+    ]
+else:
+    # Linking 'icu' will pull in the stubdata library,
+    # which the shell doesn't want, so link the other bits.
+    USE_LIBS += [
+        'icui18n',
+        'icuuc',
+    ]
 
 USE_LIBS += [
     'nspr',
@@ -708,7 +707,7 @@ if CONFIG['_MSC_VER']:
     CXXFLAGS += ['-wd4577']
     CXXFLAGS += ['-wd4312']
 
-if CONFIG['OS_ARCH'] not in ('WINNT', 'HP-UX'):
+if CONFIG['OS_ARCH'] not in ('WINNT'):
     OS_LIBS += [
         'm',
     ]
diff --git a/js/src/old-configure.in b/js/src/old-configure.in
index 1736cc5d4..8abea5956 100644
--- a/js/src/old-configure.in
+++ b/js/src/old-configure.in
@@ -734,12 +734,14 @@ case "$target" in
           dnl VS2012+ defaults to -arch:SSE2. We want to target nothing
           dnl more recent, so set that explicitly here unless another
           dnl target arch has already been set.
+          changequote(,)
           if test -z `echo $CFLAGS | grep -i [-/]arch:` ; then
             CFLAGS="$CFLAGS -arch:SSE2"
-            fi
+          fi
           if test -z `echo $CXXFLAGS | grep -i [-/]arch:` ; then
             CXXFLAGS="$CXXFLAGS -arch:SSE2"
           fi
+          changequote([,])
         fi
         dnl VS2013+ requires -FS when parallel building by make -jN.
         dnl If nothing, compiler sometimes causes C1041 error.
@@ -1534,6 +1536,14 @@ MOZ_ARG_ENABLE_STRING(ui-locale,
 AC_SUBST(MOZ_UI_LOCALE)
 
 dnl ========================================================
+dnl Build the tests?
+dnl ========================================================
+MOZ_ARG_ENABLE_BOOL(tests,
+[  --enable-tests          Build test libraries & programs],
+    ENABLE_TESTS=1,
+    ENABLE_TESTS= )
+
+dnl ========================================================
 dnl =
 dnl = Module specific options
 dnl =
@@ -2091,6 +2101,8 @@ AC_SUBST(MOZ_DEBUG_LDFLAGS)
 AC_SUBST(WARNINGS_AS_ERRORS)
 AC_SUBST(LIBICONV)
 
+AC_SUBST(ENABLE_TESTS)
+
 AC_SUBST(ENABLE_STRIP)
 AC_SUBST(PKG_SKIP_STRIP)
 AC_SUBST(INCREMENTAL_LINKER)
@@ -2244,8 +2256,6 @@ AC_SUBST(JS_LIBRARY_NAME)
 AC_SUBST(JS_CONFIG_MOZ_JS_LIBS)
 AC_SUBST(JS_CONFIG_LIBS)
 
-MOZ_SUBCONFIGURE_JEMALLOC()
-
 # Avoid using obsolete NSPR features
 AC_DEFINE(NO_NSPR_10_SUPPORT)
 
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index cc68c90d5..8d144417a 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -893,7 +893,6 @@ SetPromiseRejectionTrackerCallback(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
-#ifdef ENABLE_INTL_API
 static bool
 AddIntlExtras(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -906,6 +905,7 @@ AddIntlExtras(JSContext* cx, unsigned argc, Value* vp)
 
     static const JSFunctionSpec funcs[] = {
         JS_SELF_HOSTED_FN("getCalendarInfo", "Intl_getCalendarInfo", 1, 0),
+        JS_SELF_HOSTED_FN("getDisplayNames", "Intl_getDisplayNames", 2, 0),
         JS_FS_END
     };
 
@@ -915,7 +915,6 @@ AddIntlExtras(JSContext* cx, unsigned argc, Value* vp)
     args.rval().setUndefined();
     return true;
 }
-#endif // ENABLE_INTL_API
 
 static bool
 EvalAndPrint(JSContext* cx, const char* bytes, size_t length,
@@ -6139,7 +6138,6 @@ static const JSFunctionSpecWithHelp shell_functions[] = {
 "Sets the callback to be invoked whenever a Promise rejection is unhandled\n"
 "or a previously-unhandled rejection becomes handled."),
 
-#ifdef ENABLE_INTL_API
     JS_FN_HELP("addIntlExtras", AddIntlExtras, 1, 0,
 "addIntlExtras(obj)",
 "Adds various not-yet-standardized Intl functions as properties on the\n"
@@ -6147,7 +6145,6 @@ static const JSFunctionSpecWithHelp shell_functions[] = {
 "functions and their behavior are experimental: don't depend upon them\n"
 "unless you're willing to update your code if these experimental APIs change\n"
 "underneath you."),
-#endif // ENABLE_INTL_API
 
     JS_FS_HELP_END
 };
diff --git a/js/src/shell/moz.build b/js/src/shell/moz.build
index 72ea8145c..e18bad238 100644
--- a/js/src/shell/moz.build
+++ b/js/src/shell/moz.build
@@ -36,7 +36,7 @@ LOCAL_INCLUDES += [
 OS_LIBS += CONFIG['EDITLINE_LIBS']
 OS_LIBS += CONFIG['MOZ_ZLIB_LIBS']
 
-if CONFIG['ENABLE_INTL_API'] and CONFIG['MOZ_ICU_DATA_ARCHIVE']:
+if CONFIG['MOZ_ICU_DATA_ARCHIVE']:
     # The ICU libraries linked into libmozjs will not include the ICU data,
     # so link it directly.
     USE_LIBS += ['icudata']
diff --git a/js/src/tests/Intl/DateTimeFormat/timeZone_backward_links.js b/js/src/tests/Intl/DateTimeFormat/timeZone_backward_links.js
index 890b1c1d5..d87abd7be 100644
--- a/js/src/tests/Intl/DateTimeFormat/timeZone_backward_links.js
+++ b/js/src/tests/Intl/DateTimeFormat/timeZone_backward_links.js
@@ -1,7 +1,7 @@
 // |reftest| skip-if(!this.hasOwnProperty("Intl"))
 
 // Generated by make_intl_data.py. DO NOT EDIT.
-// tzdata version = 2018c
+// tzdata version = 2018e
 
 const tzMapper = [
     x => x,
diff --git a/js/src/tests/Intl/DateTimeFormat/timeZone_backzone.js b/js/src/tests/Intl/DateTimeFormat/timeZone_backzone.js
index 19fd871eb..b96dac96f 100644
--- a/js/src/tests/Intl/DateTimeFormat/timeZone_backzone.js
+++ b/js/src/tests/Intl/DateTimeFormat/timeZone_backzone.js
@@ -1,7 +1,7 @@
 // |reftest| skip-if(!this.hasOwnProperty("Intl"))
 
 // Generated by make_intl_data.py. DO NOT EDIT.
-// tzdata version = 2018c
+// tzdata version = 2018e
 
 const tzMapper = [
     x => x,
diff --git a/js/src/tests/Intl/DateTimeFormat/timeZone_backzone_links.js b/js/src/tests/Intl/DateTimeFormat/timeZone_backzone_links.js
index 34425acec..66ef3075d 100644
--- a/js/src/tests/Intl/DateTimeFormat/timeZone_backzone_links.js
+++ b/js/src/tests/Intl/DateTimeFormat/timeZone_backzone_links.js
@@ -1,7 +1,7 @@
 // |reftest| skip-if(!this.hasOwnProperty("Intl"))
 
 // Generated by make_intl_data.py. DO NOT EDIT.
-// tzdata version = 2018c
+// tzdata version = 2018e
 
 const tzMapper = [
     x => x,
diff --git a/js/src/tests/Intl/DateTimeFormat/timeZone_notbackward_links.js b/js/src/tests/Intl/DateTimeFormat/timeZone_notbackward_links.js
index 8b2dedec2..8d44204bc 100644
--- a/js/src/tests/Intl/DateTimeFormat/timeZone_notbackward_links.js
+++ b/js/src/tests/Intl/DateTimeFormat/timeZone_notbackward_links.js
@@ -1,7 +1,7 @@
 // |reftest| skip-if(!this.hasOwnProperty("Intl"))
 
 // Generated by make_intl_data.py. DO NOT EDIT.
-// tzdata version = 2018c
+// tzdata version = 2018e
 
 const tzMapper = [
     x => x,
diff --git a/js/src/tests/Intl/PluralRules/resolvedOptions-overridden-species.js b/js/src/tests/Intl/PluralRules/resolvedOptions-overridden-species.js
deleted file mode 100644
index f5f5b62a8..000000000
--- a/js/src/tests/Intl/PluralRules/resolvedOptions-overridden-species.js
+++ /dev/null
@@ -1,27 +0,0 @@
-// |reftest| skip-if(!this.hasOwnProperty("Intl")||!this.hasOwnProperty("addIntlExtras"))
-
-// Tests the PluralRules.resolvedOptions function for overriden Array[Symbol.species].
-
-addIntlExtras(Intl);
-
-var pl = new Intl.PluralRules("de");
-
-Object.defineProperty(Array, Symbol.species, {
-    value: function() {
-        return new Proxy(["?"], {
-            get(t, pk, r) {
-                return Reflect.get(t, pk, r);
-            },
-            defineProperty(t, pk) {
-                return true;
-            }
-        });
-    }
-});
-
-var pluralCategories = pl.resolvedOptions().pluralCategories;
-
-assertEqArray(pluralCategories, ["one", "other"]);
-
-if (typeof reportCompare === "function")
-    reportCompare(0, 0);
diff --git a/js/src/tests/Intl/getCanonicalLocales-overridden-species.js b/js/src/tests/Intl/getCanonicalLocales-overridden-species.js
deleted file mode 100644
index 858735b58..000000000
--- a/js/src/tests/Intl/getCanonicalLocales-overridden-species.js
+++ /dev/null
@@ -1,23 +0,0 @@
-// |reftest| skip-if(!this.hasOwnProperty("Intl"))
-
-// Tests the getCanonicalLocales function for overriden Array[Symbol.species].
-
-Object.defineProperty(Array, Symbol.species, {
-    value: function() {
-        return new Proxy(["?"], {
-            get(t, pk, r) {
-                return Reflect.get(t, pk, r);
-            },
-            defineProperty(t, pk) {
-                return true;
-            }
-        });
-    }
-});
-
-var arr = Intl.getCanonicalLocales("de-x-private");
-
-assertEqArray(arr, ["de-x-private"]);
-
-if (typeof reportCompare === "function")
-    reportCompare(0, 0);
diff --git a/js/src/tests/Intl/getDisplayNames.js b/js/src/tests/Intl/getDisplayNames.js
new file mode 100644
index 000000000..ad2dbc940
--- /dev/null
+++ b/js/src/tests/Intl/getDisplayNames.js
@@ -0,0 +1,238 @@
+// |reftest| skip-if(!this.hasOwnProperty('Intl')||!this.hasOwnProperty('addIntlExtras'))
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Tests the getCalendarInfo function with a diverse set of arguments.
+
+/*
+ * Test if getDisplayNames return value matches expected values.
+ */
+function checkDisplayNames(names, expected)
+{
+  assertEq(Object.getPrototypeOf(names), Object.prototype);
+
+  assertEq(names.locale, expected.locale);
+  assertEq(names.style, expected.style);
+
+  const nameValues = names.values;
+  const expectedValues = expected.values;
+
+  const nameValuesKeys = Object.getOwnPropertyNames(nameValues).sort();
+  const expectedValuesKeys = Object.getOwnPropertyNames(expectedValues).sort();
+
+  assertEqArray(nameValuesKeys, expectedValuesKeys);
+
+  for (let key of expectedValuesKeys)
+    assertEq(nameValues[key], expectedValues[key]);
+}
+
+addIntlExtras(Intl);
+
+let gDN = Intl.getDisplayNames;
+
+assertEq(gDN.length, 2);
+
+checkDisplayNames(gDN('en-US', {
+}), {
+  locale: 'en-US',
+  style: 'long',
+  values: {}
+});
+
+checkDisplayNames(gDN('en-US', {
+  keys: [
+    'dates/gregorian/weekdays/wednesday'
+  ],
+  style: 'narrow'
+}), {
+  locale: 'en-US',
+  style: 'narrow',
+  values: {
+    'dates/gregorian/weekdays/wednesday': 'W'
+  }
+});
+
+checkDisplayNames(gDN('en-US', {
+  keys: [
+    'dates/fields/year',
+    'dates/fields/month',
+    'dates/fields/week',
+    'dates/fields/day',
+    'dates/gregorian/months/january',
+    'dates/gregorian/months/february',
+    'dates/gregorian/months/march',
+    'dates/gregorian/weekdays/tuesday'
+  ]
+}), {
+  locale: 'en-US',
+  style: 'long',
+  values: {
+    'dates/fields/year': 'year',
+    'dates/fields/month': 'month',
+    'dates/fields/week': 'week',
+    'dates/fields/day': 'day',
+    'dates/gregorian/months/january': 'January',
+    'dates/gregorian/months/february': 'February',
+    'dates/gregorian/months/march': 'March',
+    'dates/gregorian/weekdays/tuesday': 'Tuesday',
+  }
+});
+
+checkDisplayNames(gDN('fr', {
+  keys: [
+    'dates/fields/year',
+    'dates/fields/day',
+    'dates/gregorian/months/october',
+    'dates/gregorian/weekdays/saturday',
+    'dates/gregorian/dayperiods/pm'
+  ]
+}), {
+  locale: 'fr',
+  style: 'long',
+  values: {
+    'dates/fields/year': 'année',
+    'dates/fields/day': 'jour',
+    'dates/gregorian/months/october': 'octobre',
+    'dates/gregorian/weekdays/saturday': 'samedi',
+    'dates/gregorian/dayperiods/pm': 'PM'
+  }
+});
+
+checkDisplayNames(gDN('it', {
+  style: 'short',
+  keys: [
+    'dates/gregorian/weekdays/thursday',
+    'dates/gregorian/months/august',
+    'dates/gregorian/dayperiods/am',
+    'dates/fields/month',
+  ]
+}), {
+  locale: 'it',
+  style: 'short',
+  values: {
+    'dates/gregorian/weekdays/thursday': 'gio',
+    'dates/gregorian/months/august': 'ago',
+    'dates/gregorian/dayperiods/am': 'AM',
+    'dates/fields/month': 'mese'
+  }
+});
+
+checkDisplayNames(gDN('ar', {
+  style: 'long',
+  keys: [
+    'dates/gregorian/weekdays/thursday',
+    'dates/gregorian/months/august',
+    'dates/gregorian/dayperiods/am',
+    'dates/fields/month',
+  ]
+}), {
+  locale: 'ar',
+  style: 'long',
+  values: {
+    'dates/gregorian/weekdays/thursday': 'الخميس',
+    'dates/gregorian/months/august': 'أغسطس',
+    'dates/gregorian/dayperiods/am': 'ص',
+    'dates/fields/month': 'الشهر'
+  }
+});
+
+/* Invalid input */
+
+assertThrowsInstanceOf(() => {
+  gDN('en-US', {
+    style: '',
+    keys: [
+      'dates/gregorian/weekdays/thursday',
+    ]
+  });
+}, RangeError);
+
+assertThrowsInstanceOf(() => {
+  gDN('en-US', {
+    style: 'bogus',
+    keys: [
+      'dates/gregorian/weekdays/thursday',
+    ]
+  });
+}, RangeError);
+
+assertThrowsInstanceOf(() => {
+  gDN('foo-X', {
+    keys: [
+      'dates/gregorian/weekdays/thursday',
+    ]
+  });
+}, RangeError);
+
+const typeErrorKeys = [
+  null,
+  'string',
+  Symbol.iterator,
+  15,
+  1,
+  3.7,
+  NaN,
+  Infinity
+];
+
+for (let keys of typeErrorKeys) {
+  assertThrowsInstanceOf(() => {
+    gDN('en-US', {
+      keys
+    });
+  }, TypeError);
+}
+
+const rangeErrorKeys = [
+  [''],
+  ['foo'],
+  ['dates/foo'],
+  ['/dates/foo'],
+  ['dates/foo/foo'],
+  ['dates/fields'],
+  ['dates/fields/'],
+  ['dates/fields/foo'],
+  ['dates/fields/foo/month'],
+  ['/dates/foo/faa/bar/baz'],
+  ['dates///bar/baz'],
+  ['dates/gregorian'],
+  ['dates/gregorian/'],
+  ['dates/gregorian/foo'],
+  ['dates/gregorian/months'],
+  ['dates/gregorian/months/foo'],
+  ['dates/gregorian/weekdays'],
+  ['dates/gregorian/weekdays/foo'],
+  ['dates/gregorian/dayperiods'],
+  ['dates/gregorian/dayperiods/foo'],
+  ['dates/gregorian/months/الشهر'],
+  [3],
+  [null],
+  ['d', 'a', 't', 'e', 's'],
+  ['datesEXTRA'],
+  ['dates/fieldsEXTRA'],
+  ['dates/gregorianEXTRA'],
+  ['dates/gregorian/monthsEXTRA'],
+  ['dates/gregorian/weekdaysEXTRA'],
+  ['dates/fields/dayperiods/amEXTRA'],
+  ['dates/gregori\u1161n/months/january'],
+  ["dates/fields/year/"],
+  ["dates/fields/month/"],
+  ["dates/fields/week/"],
+  ["dates/fields/day/"],
+  ["dates/gregorian/months/january/"],
+  ["dates/gregorian/weekdays/saturday/"],
+  ["dates/gregorian/dayperiods/am/"],
+  ["dates/fields/months/january/"],
+];
+
+for (let keys of rangeErrorKeys) {
+  assertThrowsInstanceOf(() => {
+    gDN('en-US', {
+      keys
+    });
+  }, RangeError);
+}
+
+if (typeof reportCompare === 'function')
+    reportCompare(0, 0);
diff --git a/js/src/tests/js1_8_5/extensions/clone-errors.js b/js/src/tests/js1_8_5/extensions/clone-errors.js
index f65578a06..d2ccea2e8 100644
--- a/js/src/tests/js1_8_5/extensions/clone-errors.js
+++ b/js/src/tests/js1_8_5/extensions/clone-errors.js
@@ -25,6 +25,7 @@ check({get x() { throw new Error("fail"); }});
 // Mismatched scopes.
 for (let [write_scope, read_scope] of [['SameProcessSameThread', 'SameProcessDifferentThread'],
                                        ['SameProcessSameThread', 'DifferentProcess'],
+                                       ['SameProcessDifferentThread', 'DifferentProcessForIndexedDB'],
                                        ['SameProcessDifferentThread', 'DifferentProcess']])
 {
   var ab = new ArrayBuffer(12);
diff --git a/js/src/tests/js1_8_5/extensions/clone-transferables.js b/js/src/tests/js1_8_5/extensions/clone-transferables.js
index 673684b95..9aad27208 100644
--- a/js/src/tests/js1_8_5/extensions/clone-transferables.js
+++ b/js/src/tests/js1_8_5/extensions/clone-transferables.js
@@ -3,11 +3,15 @@
 // http://creativecommons.org/licenses/publicdomain/
 
 function* buffer_options() {
-  for (var scope of ["SameProcessSameThread", "SameProcessDifferentThread", "DifferentProcess"]) {
-    for (var size of [0, 8, 16, 200, 1000, 4096, 8192, 65536]) {
-      yield { scope, size };
+    for (var scope of ["SameProcessSameThread",
+                       "SameProcessDifferentThread",
+                       "DifferentProcess",
+                       "DifferentProcessForIndexedDB"])
+    {
+        for (var size of [0, 8, 16, 200, 1000, 4096, 8192, 65536]) {
+            yield { scope, size };
+        }
     }
-  }
 }
 
 
diff --git a/js/src/threading/windows/ConditionVariable.cpp b/js/src/threading/windows/ConditionVariable.cpp
index 3c75a0f27..92e0249b7 100644
--- a/js/src/threading/windows/ConditionVariable.cpp
+++ b/js/src/threading/windows/ConditionVariable.cpp
@@ -54,8 +54,8 @@ js::ConditionVariable::notify_all()
 void
 js::ConditionVariable::wait(UniqueLock<Mutex>& lock)
 {
-  CRITICAL_SECTION* cs = &lock.lock.platformData()->criticalSection;
-  bool r = SleepConditionVariableCS(&platformData()->cv_, cs, INFINITE);
+  SRWLOCK* srwlock = &lock.lock.platformData()->lock;
+  bool r = SleepConditionVariableSRW(&platformData()->cv_, srwlock, INFINITE, 0);
   MOZ_RELEASE_ASSERT(r);
 }
 
@@ -70,7 +70,7 @@ js::CVStatus
 js::ConditionVariable::wait_for(UniqueLock<Mutex>& lock,
                                 const mozilla::TimeDuration& rel_time)
 {
-  CRITICAL_SECTION* cs = &lock.lock.platformData()->criticalSection;
+  SRWLOCK* srwlock = &lock.lock.platformData()->lock;
 
   // Note that DWORD is unsigned, so we have to be careful to clamp at 0.
   // If rel_time is Forever, then ToMilliseconds is +inf, which evaluates as
@@ -82,7 +82,7 @@ js::ConditionVariable::wait_for(UniqueLock<Mutex>& lock,
                  ? INFINITE
                  : static_cast<DWORD>(msecd);
 
-  BOOL r = SleepConditionVariableCS(&platformData()->cv_, cs, msec);
+  BOOL r = SleepConditionVariableSRW(&platformData()->cv_, srwlock, msec, 0);
   if (r)
     return CVStatus::NoTimeout;
   MOZ_RELEASE_ASSERT(GetLastError() == ERROR_TIMEOUT);
diff --git a/js/src/threading/windows/MutexImpl.cpp b/js/src/threading/windows/MutexImpl.cpp
index 385d1c8de..e838459b5 100644
--- a/js/src/threading/windows/MutexImpl.cpp
+++ b/js/src/threading/windows/MutexImpl.cpp
@@ -13,35 +13,6 @@
 #include "threading/Mutex.h"
 #include "threading/windows/MutexPlatformData.h"
 
-namespace {
-
-// We build with a toolkit that supports WinXP, so we have to probe
-// for modern features at runtime. This is necessary because Vista and
-// later automatically allocate and subsequently leak a debug info
-// object for each critical section that we allocate unless we tell it
-// not to. In order to tell it not to, we need the extra flags field
-// provided by the Ex version of InitializeCriticalSection.
-struct MutexNativeImports
-{
-  using InitializeCriticalSectionExT = BOOL (WINAPI*)(CRITICAL_SECTION*, DWORD, DWORD);
-  InitializeCriticalSectionExT InitializeCriticalSectionEx;
-
-  MutexNativeImports() {
-    HMODULE kernel32_dll = GetModuleHandle("kernel32.dll");
-    MOZ_RELEASE_ASSERT(kernel32_dll != NULL);
-    InitializeCriticalSectionEx = reinterpret_cast<InitializeCriticalSectionExT>(
-      GetProcAddress(kernel32_dll, "InitializeCriticalSectionEx"));
-  }
-
-  bool hasInitializeCriticalSectionEx() const {
-    return InitializeCriticalSectionEx;
-  }
-};
-
-static MutexNativeImports NativeImports;
-
-} // (anonymous namespace)
-
 js::detail::MutexImpl::MutexImpl()
 {
   AutoEnterOOMUnsafeRegion oom;
@@ -49,18 +20,7 @@ js::detail::MutexImpl::MutexImpl()
   if (!platformData_)
     oom.crash("js::Mutex::Mutex");
 
-  // This number was adopted from NSPR.
-  const static DWORD LockSpinCount = 1500;
-  BOOL r;
-  if (NativeImports.hasInitializeCriticalSectionEx()) {
-    r = NativeImports.InitializeCriticalSectionEx(&platformData()->criticalSection,
-                                                  LockSpinCount,
-                                                  CRITICAL_SECTION_NO_DEBUG_INFO);
-  } else {
-    r = InitializeCriticalSectionAndSpinCount(&platformData()->criticalSection,
-                                              LockSpinCount);
-  }
-  MOZ_RELEASE_ASSERT(r);
+  InitializeSRWLock(&platformData()->lock);
 }
 
 js::detail::MutexImpl::~MutexImpl()
@@ -68,18 +28,17 @@ js::detail::MutexImpl::~MutexImpl()
   if (!platformData_)
     return;
 
-  DeleteCriticalSection(&platformData()->criticalSection);
   js_delete(platformData());
 }
 
 void
 js::detail::MutexImpl::lock()
 {
-  EnterCriticalSection(&platformData()->criticalSection);
+  AcquireSRWLockExclusive(&platformData()->lock);
 }
 
 void
 js::detail::MutexImpl::unlock()
 {
-  LeaveCriticalSection(&platformData()->criticalSection);
+  ReleaseSRWLockExclusive(&platformData()->lock);
 }
diff --git a/js/src/threading/windows/MutexPlatformData.h b/js/src/threading/windows/MutexPlatformData.h
index fbe7fc80d..1d741c5d0 100644
--- a/js/src/threading/windows/MutexPlatformData.h
+++ b/js/src/threading/windows/MutexPlatformData.h
@@ -13,7 +13,7 @@
 
 struct js::detail::MutexImpl::PlatformData
 {
-  CRITICAL_SECTION criticalSection;
+  SRWLOCK lock;
 };
 
 #endif // platform_win_MutexPlatformData_h
diff --git a/js/src/vm/DateTime.cpp b/js/src/vm/DateTime.cpp
index e35ad4285..ba3145af2 100644
--- a/js/src/vm/DateTime.cpp
+++ b/js/src/vm/DateTime.cpp
@@ -13,9 +13,7 @@
 #include "jsutil.h"
 
 #include "js/Date.h"
-#if ENABLE_INTL_API
 #include "unicode/timezone.h"
-#endif
 
 using mozilla::Atomic;
 using mozilla::ReleaseAcquire;
@@ -333,7 +331,7 @@ JS::ResetTimeZone()
 {
     js::DateTimeInfo::updateTimeZoneAdjustment();
 
-#if ENABLE_INTL_API && defined(ICU_TZ_HAS_RECREATE_DEFAULT)
+#if defined(ICU_TZ_HAS_RECREATE_DEFAULT)
     TZInfo.acquire();
     TZInfo.status = IcuTimeZoneInfo::NeedsUpdate;
     TZInfo.release();
@@ -343,7 +341,7 @@ JS::ResetTimeZone()
 void
 js::ResyncICUDefaultTimeZone()
 {
-#if ENABLE_INTL_API && defined(ICU_TZ_HAS_RECREATE_DEFAULT)
+#if defined(ICU_TZ_HAS_RECREATE_DEFAULT)
     TZInfo.acquire();
     if (TZInfo.status == IcuTimeZoneInfo::NeedsUpdate) {
         icu::TimeZone::recreateDefault();
diff --git a/js/src/vm/GlobalObject.cpp b/js/src/vm/GlobalObject.cpp
index 280548cd6..c90b6b85f 100644
--- a/js/src/vm/GlobalObject.cpp
+++ b/js/src/vm/GlobalObject.cpp
@@ -17,9 +17,7 @@
 
 #include "builtin/AtomicsObject.h"
 #include "builtin/Eval.h"
-#if EXPOSE_INTL_API
-# include "builtin/Intl.h"
-#endif
+#include "builtin/Intl.h"
 #include "builtin/MapObject.h"
 #include "builtin/ModuleObject.h"
 #include "builtin/Object.h"
diff --git a/js/src/vm/HelperThreads.cpp b/js/src/vm/HelperThreads.cpp
index 7381a97b5..bd29d0c79 100644
--- a/js/src/vm/HelperThreads.cpp
+++ b/js/src/vm/HelperThreads.cpp
@@ -1144,7 +1144,7 @@ js::GCParallelTask::runFromMainThread(JSRuntime* rt)
     MOZ_ASSERT(state == NotStarted);
     MOZ_ASSERT(js::CurrentThreadCanAccessRuntime(rt));
     uint64_t timeStart = PRMJ_Now();
-    run();
+    runTask();
     duration_ = PRMJ_Now() - timeStart;
 }
 
@@ -1155,7 +1155,7 @@ js::GCParallelTask::runFromHelperThread(AutoLockHelperThreadState& locked)
         AutoUnlockHelperThreadState parallelSection(locked);
         gc::AutoSetThreadIsPerformingGC performingGC;
         uint64_t timeStart = PRMJ_Now();
-        run();
+        runTask();
         duration_ = PRMJ_Now() - timeStart;
     }
 
diff --git a/js/src/vm/Initialization.cpp b/js/src/vm/Initialization.cpp
index 05cc087cc..39acdf9a8 100644
--- a/js/src/vm/Initialization.cpp
+++ b/js/src/vm/Initialization.cpp
@@ -20,10 +20,8 @@
 #include "jit/ExecutableAllocator.h"
 #include "jit/Ion.h"
 #include "js/Utility.h"
-#if ENABLE_INTL_API
 #include "unicode/uclean.h"
 #include "unicode/utypes.h"
-#endif // ENABLE_INTL_API
 #include "vm/DateTime.h"
 #include "vm/HelperThreads.h"
 #include "vm/Runtime.h"
@@ -113,12 +111,10 @@ JS::detail::InitWithFailureDiagnostic(bool isDebugBuild)
 
     js::DateTimeInfo::init();
 
-#if EXPOSE_INTL_API
     UErrorCode err = U_ZERO_ERROR;
     u_init(&err);
     if (U_FAILURE(err))
         return "u_init() failed";
-#endif // EXPOSE_INTL_API
 
     RETURN_IF_FAIL(js::CreateHelperThreadsState());
     RETURN_IF_FAIL(FutexRuntime::initialize());
@@ -171,9 +167,7 @@ JS_ShutDown(void)
     // to do it only when PRMJ_Now is eventually called.
     PRMJ_NowShutdown();
 
-#if EXPOSE_INTL_API
     u_cleanup();
-#endif // EXPOSE_INTL_API
 
     if (!JSRuntime::hasLiveRuntimes())
         js::jit::ReleaseProcessExecutableMemory();
@@ -188,11 +182,7 @@ JS_SetICUMemoryFunctions(JS_ICUAllocFn allocFn, JS_ICUReallocFn reallocFn, JS_IC
                "must call JS_SetICUMemoryFunctions before any other JSAPI "
                "operation (including JS_Init)");
 
-#if EXPOSE_INTL_API
     UErrorCode status = U_ZERO_ERROR;
     u_setMemoryFunctions(/* context = */ nullptr, allocFn, reallocFn, freeFn, &status);
     return U_SUCCESS(status);
-#else
-    return true;
-#endif
 }
diff --git a/js/src/vm/Runtime.cpp b/js/src/vm/Runtime.cpp
index 0d6a3922c..174e23594 100644
--- a/js/src/vm/Runtime.cpp
+++ b/js/src/vm/Runtime.cpp
@@ -213,11 +213,6 @@ JSRuntime::JSRuntime(JSRuntime* parentRuntime)
     warningReporter(nullptr),
     buildIdOp(nullptr),
     propertyRemovals(0),
-#if !EXPOSE_INTL_API
-    thousandsSeparator(0),
-    decimalSeparator(0),
-    numGrouping(0),
-#endif
     keepAtoms_(0),
     trustedPrincipals_(nullptr),
     beingDestroyed_(false),
@@ -330,8 +325,7 @@ JSRuntime::init(uint32_t maxbytes, uint32_t maxNurseryBytes)
     /* The garbage collector depends on everything before this point being initialized. */
     gcInitialized = true;
 
-    if (!InitRuntimeNumberState(this))
-        return false;
+    InitRuntimeNumberState(this);
 
     JS::ResetTimeZone();
 
@@ -425,10 +419,6 @@ JSRuntime::destroyRuntime()
      */
     FreeScriptData(this, lock);
 
-#if !EXPOSE_INTL_API
-    FinishRuntimeNumberState(this);
-#endif
-
     gc.finish();
     atomsCompartment_ = nullptr;
 
diff --git a/js/src/vm/Runtime.h b/js/src/vm/Runtime.h
index 734543c4e..735adadf2 100644
--- a/js/src/vm/Runtime.h
+++ b/js/src/vm/Runtime.h
@@ -978,13 +978,6 @@ struct JSRuntime : public JS::shadow::Runtime,
      */
     uint32_t            propertyRemovals;
 
-#if !EXPOSE_INTL_API
-    /* Number localization, used by jsnum.cpp. */
-    const char*         thousandsSeparator;
-    const char*         decimalSeparator;
-    const char*         numGrouping;
-#endif
-
   private:
     mozilla::Maybe<js::SharedImmutableStringsCache> sharedImmutableStrings_;
 
diff --git a/js/src/vm/SelfHosting.cpp b/js/src/vm/SelfHosting.cpp
index c7e7cc863..3e7baccad 100644
--- a/js/src/vm/SelfHosting.cpp
+++ b/js/src/vm/SelfHosting.cpp
@@ -189,6 +189,22 @@ intrinsic_IsInstanceOfBuiltin(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
+template<typename T>
+static bool
+intrinsic_GuardToBuiltin(JSContext* cx, unsigned argc, Value* vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    MOZ_ASSERT(args.length() == 1);
+    MOZ_ASSERT(args[0].isObject());
+
+    if (args[0].toObject().is<T>()) {
+        args.rval().setObject(args[0].toObject());
+        return true;
+    }
+    args.rval().setNull();
+    return true;
+}
+
 /**
  * Self-hosting intrinsic returning the original constructor for a builtin
  * the name of which is the first and only argument.
@@ -2174,11 +2190,7 @@ static const JSFunctionSpec intrinsic_functions[] = {
     JS_FN("std_String_trimRight",                str_trimRight,                0,0),
     JS_FN("std_String_toLocaleLowerCase",        str_toLocaleLowerCase,        0,0),
     JS_FN("std_String_toLocaleUpperCase",        str_toLocaleUpperCase,        0,0),
-#if !EXPOSE_INTL_API
-    JS_FN("std_String_localeCompare",            str_localeCompare,            1,0),
-#else
     JS_FN("std_String_normalize",                str_normalize,                0,0),
-#endif
     JS_FN("std_String_concat",                   str_concat,                   1,0),
     
     JS_FN("std_TypedArray_buffer",               js::TypedArray_bufferGetter,  1,0),
@@ -2265,18 +2277,18 @@ static const JSFunctionSpec intrinsic_functions[] = {
 
     JS_FN("_SetCanonicalName",       intrinsic_SetCanonicalName,        2,0),
 
-    JS_INLINABLE_FN("IsArrayIterator",
-                    intrinsic_IsInstanceOfBuiltin<ArrayIteratorObject>, 1,0,
-                    IntrinsicIsArrayIterator),
-    JS_INLINABLE_FN("IsMapIterator",
-                    intrinsic_IsInstanceOfBuiltin<MapIteratorObject>,   1,0,
-                    IntrinsicIsMapIterator),
-    JS_INLINABLE_FN("IsSetIterator",
-                    intrinsic_IsInstanceOfBuiltin<SetIteratorObject>,   1,0,
-                    IntrinsicIsSetIterator),
-    JS_INLINABLE_FN("IsStringIterator",
-                    intrinsic_IsInstanceOfBuiltin<StringIteratorObject>, 1,0,
-                    IntrinsicIsStringIterator),
+    JS_INLINABLE_FN("GuardToArrayIterator",
+                    intrinsic_GuardToBuiltin<ArrayIteratorObject>, 1,0,
+                    IntrinsicGuardToArrayIterator),
+    JS_INLINABLE_FN("GuardToMapIterator",
+                    intrinsic_GuardToBuiltin<MapIteratorObject>,   1,0,
+                    IntrinsicGuardToMapIterator),
+    JS_INLINABLE_FN("GuardToSetIterator",
+                    intrinsic_GuardToBuiltin<SetIteratorObject>,   1,0,
+                    IntrinsicGuardToSetIterator),
+    JS_INLINABLE_FN("GuardToStringIterator",
+                    intrinsic_GuardToBuiltin<StringIteratorObject>, 1,0,
+                    IntrinsicGuardToStringIterator),
 
     JS_FN("_CreateMapIterationResultPair", intrinsic_CreateMapIterationResultPair, 0, 0),
     JS_INLINABLE_FN("_GetNextMapEntryForIterator", intrinsic_GetNextMapEntryForIterator, 2,0,
@@ -2377,7 +2389,12 @@ static const JSFunctionSpec intrinsic_functions[] = {
     JS_FN("CallStarGeneratorMethodIfWrapped",
           CallNonGenericSelfhostedMethod<Is<StarGeneratorObject>>, 2, 0),
 
+    JS_INLINABLE_FN("GuardToMapObject", intrinsic_GuardToBuiltin<MapObject>, 1, 0,
+          IntrinsicGuardToMapObject),
     JS_FN("IsWeakSet", intrinsic_IsInstanceOfBuiltin<WeakSetObject>, 1,0),
+
+    JS_INLINABLE_FN("GuardToSetObject", intrinsic_GuardToBuiltin<SetObject>, 1, 0,
+          IntrinsicGuardToSetObject),
     JS_FN("CallWeakSetMethodIfWrapped",
           CallNonGenericSelfhostedMethod<Is<WeakSetObject>>, 2, 0),
 
@@ -2438,6 +2455,7 @@ static const JSFunctionSpec intrinsic_functions[] = {
     JS_FN("intl_FormatDateTime", intl_FormatDateTime, 2,0),
     JS_FN("intl_FormatNumber", intl_FormatNumber, 2,0),
     JS_FN("intl_GetCalendarInfo", intl_GetCalendarInfo, 1,0),
+    JS_FN("intl_ComputeDisplayNames", intl_ComputeDisplayNames, 3,0),
     JS_FN("intl_IsValidTimeZoneName", intl_IsValidTimeZoneName, 1,0),
     JS_FN("intl_NumberFormat", intl_NumberFormat, 2,0),
     JS_FN("intl_NumberFormat_availableLocales", intl_NumberFormat_availableLocales, 0,0),
diff --git a/js/src/vm/StructuredClone.cpp b/js/src/vm/StructuredClone.cpp
index 3a062c3b8..42e909000 100644
--- a/js/src/vm/StructuredClone.cpp
+++ b/js/src/vm/StructuredClone.cpp
@@ -160,16 +160,16 @@ template<typename T, typename AllocPolicy>
 struct BufferIterator {
     typedef mozilla::BufferList<AllocPolicy> BufferList;
 
-    explicit BufferIterator(BufferList& buffer)
+    explicit BufferIterator(const BufferList& buffer)
         : mBuffer(buffer)
         , mIter(buffer.Iter())
     {
         JS_STATIC_ASSERT(8 % sizeof(T) == 0);
     }
 
-    BufferIterator(const BufferIterator& other)
-        : mBuffer(other.mBuffer)
-        , mIter(other.mIter)
+    explicit BufferIterator(const JSStructuredCloneData& data)
+      : mBuffer(data.bufList_)
+      , mIter(data.Start())
     {
     }
 
@@ -228,17 +228,26 @@ struct BufferIterator {
         return mIter.HasRoomFor(sizeof(T));
     }
 
-    BufferList& mBuffer;
+    const BufferList& mBuffer;
     typename BufferList::IterImpl mIter;
 };
 
+// SCOutput provides an interface to write raw data -- eg uint64_ts, doubles,
+// arrays of bytes -- into a structured clone data output stream. It also knows
+// how to free any transferable data within that stream.
+//
+// Note that it contains a full JSStructuredCloneData object, which holds the
+// callbacks necessary to read/write/transfer/free the data. For the purpose of
+// this class, only the freeTransfer callback is relevant; the rest of the callbacks
+// are used by the higher-level JSStructuredCloneWriter interface.
 struct SCOutput {
   public:
-    using Iter = BufferIterator<uint64_t, TempAllocPolicy>;
+    using Iter = BufferIterator<uint64_t, SystemAllocPolicy>;
 
-    explicit SCOutput(JSContext* cx);
+    SCOutput(JSContext* cx, JS::StructuredCloneScope scope);
 
     JSContext* context() const { return cx; }
+    JS::StructuredCloneScope scope() const { return buf.scope(); }
 
     bool write(uint64_t u);
     bool writePair(uint32_t tag, uint32_t data);
@@ -251,22 +260,25 @@ struct SCOutput {
     template <class T>
     bool writeArray(const T* p, size_t nbytes);
 
-    bool extractBuffer(JSStructuredCloneData* data);
-    void discardTransferables(const JSStructuredCloneCallbacks* cb, void* cbClosure);
+    void setCallbacks(const JSStructuredCloneCallbacks* callbacks,
+                      void* closure,
+                      OwnTransferablePolicy policy)
+    {
+        buf.setCallbacks(callbacks, closure, policy);
+    }
+    void extractBuffer(JSStructuredCloneData* data) { *data = Move(buf); }
+    void discardTransferables();
 
     uint64_t tell() const { return buf.Size(); }
     uint64_t count() const { return buf.Size() / sizeof(uint64_t); }
-    Iter iter() {
-        return BufferIterator<uint64_t, TempAllocPolicy>(buf);
-    }
+    Iter iter() { return Iter(buf); }
 
     size_t offset(Iter dest) {
         return dest - iter();
     }
 
-  private:
     JSContext* cx;
-    mozilla::BufferList<TempAllocPolicy> buf;
+    JSStructuredCloneData buf;
 };
 
 class SCInput {
@@ -356,13 +368,6 @@ struct JSStructuredCloneReader {
     // be valid cross-process.)
     JS::StructuredCloneScope allowedScope;
 
-    // The scope the buffer was generated for (what sort of buffer it is.) The
-    // scope is not just a permissions thing; it also affects the storage
-    // format (eg a Transferred ArrayBuffer can be stored as a pointer for
-    // SameProcessSameThread but must have its contents in the clone buffer for
-    // DifferentProcess.)
-    JS::StructuredCloneScope storedScope;
-
     // Stack of objects with properties remaining to be read.
     AutoValueVector objs;
 
@@ -386,13 +391,15 @@ struct JSStructuredCloneWriter {
                                      const JSStructuredCloneCallbacks* cb,
                                      void* cbClosure,
                                      const Value& tVal)
-        : out(cx), scope(scope), objs(out.context()),
+        : out(cx, scope), objs(out.context()),
           counts(out.context()), entries(out.context()),
-          memory(out.context()), callbacks(cb),
-          closure(cbClosure), transferable(out.context(), tVal),
+          memory(out.context()),
+          transferable(out.context(), tVal),
           transferableObjects(out.context(), GCHashSet<JSObject*>(cx)),
           cloneDataPolicy(cloneDataPolicy)
-    {}
+    {
+        out.setCallbacks(cb, cbClosure, OwnTransferablePolicy::NoTransferables);
+    }
 
     ~JSStructuredCloneWriter();
 
@@ -408,17 +415,10 @@ struct JSStructuredCloneWriter {
 
     SCOutput& output() { return out; }
 
-    bool extractBuffer(JSStructuredCloneData* data) {
-        bool success = out.extractBuffer(data);
-        if (success) {
-            data->setOptionalCallbacks(callbacks, closure,
-                                       OwnTransferablePolicy::OwnsTransferablesIfAny);
-        }
-        return success;
+    void extractBuffer(JSStructuredCloneData* newData) {
+        out.extractBuffer(newData);
     }
 
-    JS::StructuredCloneScope cloneScope() const { return scope; }
-
   private:
     JSStructuredCloneWriter() = delete;
     JSStructuredCloneWriter(const JSStructuredCloneWriter&) = delete;
@@ -449,9 +449,6 @@ struct JSStructuredCloneWriter {
 
     SCOutput out;
 
-    // The (address space, thread) scope within which this clone is valid.
-    JS::StructuredCloneScope scope;
-
     // Vector of objects with properties remaining to be written.
     //
     // NB: These can span multiple compartments, so the compartment must be
@@ -477,12 +474,6 @@ struct JSStructuredCloneWriter {
                                   SystemAllocPolicy>;
     Rooted<CloneMemory> memory;
 
-    // The user defined callbacks that will be used for cloning.
-    const JSStructuredCloneCallbacks* callbacks;
-
-    // Any value passed to JS_WriteStructuredClone.
-    void* closure;
-
     // Set of transferable objects
     RootedValue transferable;
     Rooted<GCHashSet<JSObject*>> transferableObjects;
@@ -542,7 +533,12 @@ WriteStructuredClone(JSContext* cx, HandleValue v, JSStructuredCloneData* bufp,
                      const Value& transferable)
 {
     JSStructuredCloneWriter w(cx, scope, cloneDataPolicy, cb, cbClosure, transferable);
-    return w.init() && w.write(v) && w.extractBuffer(bufp);
+    if (!w.init())
+        return false;
+    if (!w.write(v))
+        return false;
+    w.extractBuffer(bufp);
+    return true;
 }
 
 bool
@@ -555,91 +551,15 @@ ReadStructuredClone(JSContext* cx, JSStructuredCloneData& data,
     return r.read(vp);
 }
 
-// If the given buffer contains Transferables, free them. Note that custom
-// Transferables will use the JSStructuredCloneCallbacks::freeTransfer() to
-// delete their transferables.
-template<typename AllocPolicy>
-static void
-DiscardTransferables(mozilla::BufferList<AllocPolicy>& buffer,
-                     const JSStructuredCloneCallbacks* cb, void* cbClosure)
-{
-    auto point = BufferIterator<uint64_t, AllocPolicy>(buffer);
-    if (point.done())
-        return; // Empty buffer
-
-    uint32_t tag, data;
-    MOZ_RELEASE_ASSERT(point.canPeek());
-    SCInput::getPair(point.peek(), &tag, &data);
-    point.next();
-
-    if (tag == SCTAG_HEADER) {
-        if (point.done())
-            return;
-
-        MOZ_RELEASE_ASSERT(point.canPeek());
-        SCInput::getPair(point.peek(), &tag, &data);
-        point.next();
-    }
-
-    if (tag != SCTAG_TRANSFER_MAP_HEADER)
-        return;
-
-    if (TransferableMapHeader(data) == SCTAG_TM_TRANSFERRED)
-        return;
-
-    // freeTransfer should not GC
-    JS::AutoSuppressGCAnalysis nogc;
-
-    if (point.done())
-        return;
-
-    uint64_t numTransferables = NativeEndian::swapFromLittleEndian(point.peek());
-    point.next();
-    while (numTransferables--) {
-        if (!point.canPeek())
-            return;
-
-        uint32_t ownership;
-        SCInput::getPair(point.peek(), &tag, &ownership);
-        point.next();
-        MOZ_ASSERT(tag >= SCTAG_TRANSFER_MAP_PENDING_ENTRY);
-        if (!point.canPeek())
-            return;
-
-        void* content;
-        SCInput::getPtr(point.peek(), &content);
-        point.next();
-        if (!point.canPeek())
-            return;
-
-        uint64_t extraData = NativeEndian::swapFromLittleEndian(point.peek());
-        point.next();
-
-        if (ownership < JS::SCTAG_TMO_FIRST_OWNED)
-            continue;
-
-        if (ownership == JS::SCTAG_TMO_ALLOC_DATA) {
-            js_free(content);
-        } else if (ownership == JS::SCTAG_TMO_MAPPED_DATA) {
-            JS_ReleaseMappedArrayBufferContents(content, extraData);
-        } else if (cb && cb->freeTransfer) {
-            cb->freeTransfer(tag, JS::TransferableOwnership(ownership), content, extraData, cbClosure);
-        } else {
-            MOZ_ASSERT(false, "unknown ownership");
-        }
-    }
-}
-
 static bool
 StructuredCloneHasTransferObjects(const JSStructuredCloneData& data)
 {
-    auto iter = data.Iter();
-
     if (data.Size() < sizeof(uint64_t))
         return false;
 
     uint64_t u;
-    data.ReadBytes(iter, reinterpret_cast<char*>(&u), sizeof(u));
+    BufferIterator<uint64_t, SystemAllocPolicy> iter(data);
+    MOZ_ALWAYS_TRUE(iter.readBytes(reinterpret_cast<char*>(&u), sizeof(u)));
     uint32_t tag = uint32_t(u >> 32);
     return (tag == SCTAG_TRANSFER_MAP_HEADER);
 }
@@ -650,7 +570,7 @@ SCInput::SCInput(JSContext* cx, JSStructuredCloneData& data)
     : cx(cx), point(data)
 {
 
-    static_assert(JSStructuredCloneData::kSegmentAlignment % 8 == 0,
+    static_assert(JSStructuredCloneData::BufferList::kSegmentAlignment % 8 == 0,
                   "structured clone buffer reads should be aligned");
     MOZ_ASSERT(data.Size() % 8 == 0);
 }
@@ -812,9 +732,8 @@ SCInput::readPtr(void** p)
     return true;
 }
 
-SCOutput::SCOutput(JSContext* cx)
-    : cx(cx)
-    , buf(0, 0, 4096, cx)
+SCOutput::SCOutput(JSContext* cx, JS::StructuredCloneScope scope)
+  : cx(cx), buf(scope)
 {
 }
 
@@ -822,7 +741,11 @@ bool
 SCOutput::write(uint64_t u)
 {
     uint64_t v = NativeEndian::swapToLittleEndian(u);
-    return buf.WriteBytes(reinterpret_cast<char*>(&v), sizeof(u));
+    if (!buf.AppendBytes(reinterpret_cast<char*>(&v), sizeof(u))) {
+        ReportOutOfMemory(context());
+        return false;
+    }
+    return true;
 }
 
 bool
@@ -883,7 +806,7 @@ SCOutput::writeArray(const T* p, size_t nelems)
 
     for (size_t i = 0; i < nelems; i++) {
         T value = swapToLittleEndian(p[i]);
-        if (!buf.WriteBytes(reinterpret_cast<char*>(&value), sizeof(value)))
+        if (!buf.AppendBytes(reinterpret_cast<char*>(&value), sizeof(value)))
             return false;
     }
 
@@ -892,7 +815,7 @@ SCOutput::writeArray(const T* p, size_t nelems)
     size_t padbytes = sizeof(uint64_t) * nwords - sizeof(T) * nelems;
     char zero = 0;
     for (size_t i = 0; i < padbytes; i++) {
-        if (!buf.WriteBytes(&zero, sizeof(zero)))
+        if (!buf.AppendBytes(&zero, sizeof(zero)))
             return false;
     }
 
@@ -927,34 +850,101 @@ SCOutput::writePtr(const void* p)
     return write(reinterpret_cast<uint64_t>(p));
 }
 
-bool
-SCOutput::extractBuffer(JSStructuredCloneData* data)
-{
-    bool success;
-    mozilla::BufferList<SystemAllocPolicy> out =
-        buf.MoveFallible<SystemAllocPolicy>(&success);
-    if (!success) {
-        ReportOutOfMemory(cx);
-        return false;
-    }
-    *data = JSStructuredCloneData(Move(out));
-    return true;
-}
-
 void
-SCOutput::discardTransferables(const JSStructuredCloneCallbacks* cb, void* cbClosure)
+SCOutput::discardTransferables()
 {
-    DiscardTransferables(buf, cb, cbClosure);
+    buf.discardTransferables();
 }
 
 } /* namespace js */
 
-JSStructuredCloneData::~JSStructuredCloneData()
+
+// If the buffer contains Transferables, free them. Note that custom
+// Transferables will use the JSStructuredCloneCallbacks::freeTransfer() to
+// delete their transferables.
+void
+JSStructuredCloneData::discardTransferables()
 {
     if (!Size())
         return;
-    if (ownTransferables_ == OwnTransferablePolicy::OwnsTransferablesIfAny)
-        DiscardTransferables(*this, callbacks_, closure_);
+
+    if (ownTransferables_ != OwnTransferablePolicy::OwnsTransferablesIfAny)
+        return;
+
+    // DifferentProcess clones cannot contain pointers, so nothing needs to be
+    // released.
+    if (scope_ == JS::StructuredCloneScope::DifferentProcess)
+        return;
+
+    FreeTransferStructuredCloneOp freeTransfer = nullptr;
+    if (callbacks_)
+        freeTransfer = callbacks_->freeTransfer;
+
+    auto point = BufferIterator<uint64_t, SystemAllocPolicy>(*this);
+    if (point.done())
+        return; // Empty buffer
+
+    uint32_t tag, data;
+    MOZ_RELEASE_ASSERT(point.canPeek());
+    SCInput::getPair(point.peek(), &tag, &data);
+    point.next();
+
+    if (tag == SCTAG_HEADER) {
+        if (point.done())
+            return;
+
+        MOZ_RELEASE_ASSERT(point.canPeek());
+        SCInput::getPair(point.peek(), &tag, &data);
+        point.next();
+    }
+
+    if (tag != SCTAG_TRANSFER_MAP_HEADER)
+        return;
+
+    if (TransferableMapHeader(data) == SCTAG_TM_TRANSFERRED)
+        return;
+
+    // freeTransfer should not GC
+    JS::AutoSuppressGCAnalysis nogc;
+
+    if (point.done())
+        return;
+
+    uint64_t numTransferables = NativeEndian::swapFromLittleEndian(point.peek());
+    point.next();
+    while (numTransferables--) {
+        if (!point.canPeek())
+            return;
+
+        uint32_t ownership;
+        SCInput::getPair(point.peek(), &tag, &ownership);
+        point.next();
+        MOZ_ASSERT(tag >= SCTAG_TRANSFER_MAP_PENDING_ENTRY);
+        if (!point.canPeek())
+            return;
+
+        void* content;
+        SCInput::getPtr(point.peek(), &content);
+        point.next();
+        if (!point.canPeek())
+            return;
+
+        uint64_t extraData = NativeEndian::swapFromLittleEndian(point.peek());
+        point.next();
+
+        if (ownership < JS::SCTAG_TMO_FIRST_OWNED)
+            continue;
+
+        if (ownership == JS::SCTAG_TMO_ALLOC_DATA) {
+            js_free(content);
+        } else if (ownership == JS::SCTAG_TMO_MAPPED_DATA) {
+            JS_ReleaseMappedArrayBufferContents(content, extraData);
+        } else if (freeTransfer) {
+            freeTransfer(tag, JS::TransferableOwnership(ownership), content, extraData, closure_);
+        } else {
+            MOZ_ASSERT(false, "unknown ownership");
+        }
+    }
 }
 
 JS_STATIC_ASSERT(JSString::MAX_LENGTH < UINT32_MAX);
@@ -962,9 +952,8 @@ JS_STATIC_ASSERT(JSString::MAX_LENGTH < UINT32_MAX);
 JSStructuredCloneWriter::~JSStructuredCloneWriter()
 {
     // Free any transferable data left lying around in the buffer
-    if (out.count()) {
-        out.discardTransferables(callbacks, closure);
-    }
+    if (out.count())
+        out.discardTransferables();
 }
 
 bool
@@ -1038,7 +1027,7 @@ JSStructuredCloneWriter::parseTransferable()
 bool
 JSStructuredCloneWriter::reportDataCloneError(uint32_t errorId)
 {
-    ReportDataCloneError(context(), callbacks, errorId);
+    ReportDataCloneError(context(), out.buf.callbacks_, errorId);
     return false;
 }
 
@@ -1454,8 +1443,8 @@ JSStructuredCloneWriter::startWrite(HandleValue v)
             return traverseSavedFrame(obj);
         }
 
-        if (callbacks && callbacks->write)
-            return callbacks->write(context(), this, obj, closure);
+        if (out.buf.callbacks_ && out.buf.callbacks_->write)
+            return out.buf.callbacks_->write(context(), this, obj, out.buf.closure_);
         /* else fall through */
     }
 
@@ -1465,7 +1454,7 @@ JSStructuredCloneWriter::startWrite(HandleValue v)
 bool
 JSStructuredCloneWriter::writeHeader()
 {
-    return out.writePair(SCTAG_HEADER, (uint32_t)scope);
+    return out.writePair(SCTAG_HEADER, (uint32_t)output().scope());
 }
 
 bool
@@ -1523,6 +1512,7 @@ JSStructuredCloneWriter::transferOwnership()
 
     JSContext* cx = context();
     RootedObject obj(cx);
+    JS::StructuredCloneScope scope = output().scope();
     for (auto tr = transferableObjects.all(); !tr.empty(); tr.popFront()) {
         obj = tr.front();
 
@@ -1555,7 +1545,9 @@ JSStructuredCloneWriter::transferOwnership()
                 return false;
             }
 
-            if (scope == JS::StructuredCloneScope::DifferentProcess) {
+            if (scope == JS::StructuredCloneScope::DifferentProcess ||
+                scope == JS::StructuredCloneScope::DifferentProcessForIndexedDB)
+            {
                 // Write Transferred ArrayBuffers in DifferentProcess scope at
                 // the end of the clone buffer, and store the offset within the
                 // buffer to where the ArrayBuffer was written. Note that this
@@ -1592,9 +1584,9 @@ JSStructuredCloneWriter::transferOwnership()
                 extraData = nbytes;
             }
         } else {
-            if (!callbacks || !callbacks->writeTransfer)
+            if (!out.buf.callbacks_ || !out.buf.callbacks_->writeTransfer)
                 return reportDataCloneError(JS_SCERR_TRANSFERABLE);
-            if (!callbacks->writeTransfer(cx, obj, closure, &tag, &ownership, &content, &extraData))
+            if (!out.buf.callbacks_->writeTransfer(cx, obj, out.buf.closure_, &tag, &ownership, &content, &extraData))
                 return false;
             MOZ_ASSERT(tag > SCTAG_TRANSFER_MAP_PENDING_ENTRY);
         }
@@ -2187,25 +2179,33 @@ JSStructuredCloneReader::readHeader()
     if (!in.getPair(&tag, &data))
         return in.reportTruncated();
 
-    if (tag != SCTAG_HEADER) {
+    JS::StructuredCloneScope storedScope;
+    if (tag == SCTAG_HEADER) {
+        MOZ_ALWAYS_TRUE(in.readPair(&tag, &data));
+        storedScope = JS::StructuredCloneScope(data);
+    } else {
         // Old structured clone buffer. We must have read it from disk.
-        storedScope = JS::StructuredCloneScope::DifferentProcess;
-        return true;
+        storedScope = JS::StructuredCloneScope::DifferentProcessForIndexedDB;
     }
 
-    MOZ_ALWAYS_TRUE(in.readPair(&tag, &data));
-    storedScope = JS::StructuredCloneScope(data);
-
-    if (data != uint32_t(JS::StructuredCloneScope::SameProcessSameThread) &&
-        data != uint32_t(JS::StructuredCloneScope::SameProcessDifferentThread) &&
-        data != uint32_t(JS::StructuredCloneScope::DifferentProcess))
+    if (storedScope < JS::StructuredCloneScope::SameProcessSameThread ||
+        storedScope > JS::StructuredCloneScope::DifferentProcessForIndexedDB)
     {
         JS_ReportErrorNumberASCII(context(), GetErrorMessage, nullptr, JSMSG_SC_BAD_SERIALIZED_DATA,
                                   "invalid structured clone scope");
         return false;
     }
+
+    if (allowedScope == JS::StructuredCloneScope::DifferentProcessForIndexedDB) {
+        // Bug 1434308 and bug 1458320 - the scopes stored in old IndexedDB
+        // clones are incorrect. Treat them as if they were DifferentProcess.
+        allowedScope = JS::StructuredCloneScope::DifferentProcess;
+        return true;
+    }
+
     if (storedScope < allowedScope) {
-        JS_ReportErrorNumberASCII(context(), GetErrorMessage, nullptr, JSMSG_SC_BAD_SERIALIZED_DATA,
+        JS_ReportErrorNumberASCII(context(), GetErrorMessage, nullptr,
+                                  JSMSG_SC_BAD_SERIALIZED_DATA,
                                   "incompatible structured clone scope");
         return false;
     }
@@ -2249,10 +2249,14 @@ JSStructuredCloneReader::readTransferMap()
             return false;
 
         if (tag == SCTAG_TRANSFER_MAP_ARRAY_BUFFER) {
-            if (storedScope == JS::StructuredCloneScope::DifferentProcess) {
+            if (allowedScope == JS::StructuredCloneScope::DifferentProcess ||
+                allowedScope == JS::StructuredCloneScope::DifferentProcessForIndexedDB)
+            {
                 // Transferred ArrayBuffers in a DifferentProcess clone buffer
-                // are treated as if they weren't Transferred at all.
-                continue;
+                // are treated as if they weren't Transferred at all. We should
+                // only see SCTAG_TRANSFER_MAP_STORED_ARRAY_BUFFER.
+                ReportDataCloneError(cx, callbacks, JS_SCERR_TRANSFERABLE);
+                return false;
             }
 
             size_t nbytes = extraData;
@@ -2586,7 +2590,7 @@ JS_StructuredClone(JSContext* cx, HandleValue value, MutableHandleValue vp,
 }
 
 JSAutoStructuredCloneBuffer::JSAutoStructuredCloneBuffer(JSAutoStructuredCloneBuffer&& other)
-    : scope_(other.scope_)
+  : scope_(other.scope()), data_(other.scope())
 {
     data_.ownTransferables_ = other.data_.ownTransferables_;
     other.steal(&data_, &version_, &data_.callbacks_, &data_.closure_);
@@ -2604,45 +2608,14 @@ JSAutoStructuredCloneBuffer::operator=(JSAutoStructuredCloneBuffer&& other)
 }
 
 void
-JSAutoStructuredCloneBuffer::clear(const JSStructuredCloneCallbacks* optionalCallbacks,
-                                   void* optionalClosure)
+JSAutoStructuredCloneBuffer::clear()
 {
-    if (!data_.Size())
-        return;
-
-    const JSStructuredCloneCallbacks* callbacks =
-        optionalCallbacks ?  optionalCallbacks : data_.callbacks_;
-    void* closure = optionalClosure ?  optionalClosure : data_.closure_;
-
-    if (data_.ownTransferables_ == OwnTransferablePolicy::OwnsTransferablesIfAny)
-        DiscardTransferables(data_, callbacks, closure);
+    data_.discardTransferables();
     data_.ownTransferables_ = OwnTransferablePolicy::NoTransferables;
     data_.Clear();
     version_ = 0;
 }
 
-bool
-JSAutoStructuredCloneBuffer::copy(const JSStructuredCloneData& srcData, uint32_t version,
-                                  const JSStructuredCloneCallbacks* callbacks,
-                                  void* closure)
-{
-    // transferable objects cannot be copied
-    if (StructuredCloneHasTransferObjects(srcData))
-        return false;
-
-    clear();
-
-    auto iter = srcData.Iter();
-    while (!iter.Done()) {
-            data_.WriteBytes(iter.Data(), iter.RemainingInSegment());
-            iter.Advance(srcData, iter.RemainingInSegment());
-    }
-
-    version_ = version;
-    data_.setOptionalCallbacks(callbacks, closure, OwnTransferablePolicy::NoTransferables);
-    return true;
-}
-
 void
 JSAutoStructuredCloneBuffer::adopt(JSStructuredCloneData&& data, uint32_t version,
                                    const JSStructuredCloneCallbacks* callbacks,
@@ -2651,7 +2624,7 @@ JSAutoStructuredCloneBuffer::adopt(JSStructuredCloneData&& data, uint32_t versio
     clear();
     data_ = Move(data);
     version_ = version;
-    data_.setOptionalCallbacks(callbacks, closure, OwnTransferablePolicy::OwnsTransferablesIfAny);
+    data_.setCallbacks(callbacks, closure, OwnTransferablePolicy::OwnsTransferablesIfAny);
 }
 
 void
@@ -2668,7 +2641,7 @@ JSAutoStructuredCloneBuffer::steal(JSStructuredCloneData* data, uint32_t* versio
     *data = Move(data_);
 
     version_ = 0;
-    data_.setOptionalCallbacks(nullptr, nullptr, OwnTransferablePolicy::NoTransferables);
+    data_.setCallbacks(nullptr, nullptr, OwnTransferablePolicy::NoTransferables);
 }
 
 bool
@@ -2782,5 +2755,5 @@ JS_ObjectNotWritten(JSStructuredCloneWriter* w, HandleObject obj)
 JS_PUBLIC_API(JS::StructuredCloneScope)
 JS_GetStructuredCloneScope(JSStructuredCloneWriter* w)
 {
-    return w->cloneScope();
+    return w->output().scope();
 }
diff --git a/js/src/wasm/AsmJS.cpp b/js/src/wasm/AsmJS.cpp
index b4f41c3d5..7fade24fb 100644
--- a/js/src/wasm/AsmJS.cpp
+++ b/js/src/wasm/AsmJS.cpp
@@ -857,7 +857,7 @@ class NumLit
   private:
     Which which_;
     union {
-        Value scalar_;
+        JS::UninitializedValue scalar_;
         SimdConstant simd_;
     } u;
 
@@ -880,7 +880,7 @@ class NumLit
 
     int32_t toInt32() const {
         MOZ_ASSERT(which_ == Fixnum || which_ == NegativeInt || which_ == BigUnsigned);
-        return u.scalar_.toInt32();
+        return u.scalar_.asValueRef().toInt32();
     }
 
     uint32_t toUint32() const {
@@ -889,17 +889,17 @@ class NumLit
 
     RawF64 toDouble() const {
         MOZ_ASSERT(which_ == Double);
-        return RawF64(u.scalar_.toDouble());
+        return RawF64(u.scalar_.asValueRef().toDouble());
     }
 
     RawF32 toFloat() const {
         MOZ_ASSERT(which_ == Float);
-        return RawF32(float(u.scalar_.toDouble()));
+        return RawF32(float(u.scalar_.asValueRef().toDouble()));
     }
 
     Value scalarValue() const {
         MOZ_ASSERT(which_ != OutOfRangeInt);
-        return u.scalar_;
+        return u.scalar_.asValueRef();
     }
 
     bool isSimd() const