Merge branch 'master' into Pale_Moon-release

# Conflicts:
#	application/palemoon/config/version.txt
#	security/manager/ssl/nsSTSPreloadList.errors
#	security/manager/ssl/nsSTSPreloadList.inc

1 files changed, 219 insertions, 312 deletions

diff --git a/js/src/jsarray.cpp b/js/src/jsarray.cpp
index 7a67c0095..ec65bce64 100644
--- a/js/src/jsarray.cpp
+++ b/js/src/jsarray.cpp
@@ -45,7 +45,6 @@
 #include "vm/Caches-inl.h"
 #include "vm/Interpreter-inl.h"
 #include "vm/NativeObject-inl.h"
-#include "vm/UnboxedObject-inl.h"
 
 using namespace js;
 using namespace js::gc;
@@ -64,7 +63,7 @@ using JS::ToUint32;
 bool
 JS::IsArray(JSContext* cx, HandleObject obj, IsArrayAnswer* answer)
 {
-    if (obj->is<ArrayObject>() || obj->is<UnboxedArrayObject>()) {
+    if (obj->is<ArrayObject>()) {
         *answer = IsArrayAnswer::Array;
         return true;
     }
@@ -100,11 +99,6 @@ js::GetLengthProperty(JSContext* cx, HandleObject obj, uint32_t* lengthp)
         return true;
     }
 
-    if (obj->is<UnboxedArrayObject>()) {
-        *lengthp = obj->as<UnboxedArrayObject>().length();
-        return true;
-    }
-
     if (obj->is<ArgumentsObject>()) {
         ArgumentsObject& argsobj = obj->as<ArgumentsObject>();
         if (!argsobj.hasOverriddenLength()) {
@@ -253,18 +247,20 @@ static bool
 GetElement(JSContext* cx, HandleObject obj, HandleObject receiver,
            uint32_t index, bool* hole, MutableHandleValue vp)
 {
-    AssertGreaterThanZero(index);
-    if (index < GetAnyBoxedOrUnboxedInitializedLength(obj)) {
-        vp.set(GetAnyBoxedOrUnboxedDenseElement(obj, uint32_t(index)));
-        if (!vp.isMagic(JS_ELEMENTS_HOLE)) {
-            *hole = false;
-            return true;
+    if (obj->isNative()) {
+        NativeObject* nobj = &obj->as<NativeObject>();
+        if (index < nobj->getDenseInitializedLength()) {
+            vp.set(nobj->getDenseElement(size_t(index)));
+            if (!vp.isMagic(JS_ELEMENTS_HOLE)) {
+                *hole = false;
+                return true;
+            }
         }
-    }
-    if (obj->is<ArgumentsObject>()) {
-        if (obj->as<ArgumentsObject>().maybeGetElement(uint32_t(index), vp)) {
-            *hole = false;
-            return true;
+        if (nobj->is<ArgumentsObject>() && index <= UINT32_MAX) {
+            if (nobj->as<ArgumentsObject>().maybeGetElement(uint32_t(index), vp)) {
+                *hole = false;
+                return true;
+            }
         }
     }
 
@@ -283,8 +279,8 @@ ElementAdder::append(JSContext* cx, HandleValue v)
 {
     MOZ_ASSERT(index_ < length_);
     if (resObj_) {
-        DenseElementResult result =
-            SetOrExtendAnyBoxedOrUnboxedDenseElements(cx, resObj_, index_, v.address(), 1);
+        NativeObject* resObj = &resObj_->as<NativeObject>();
+        DenseElementResult result = resObj->setOrExtendDenseElements(cx, index_, v.address(), 1);
         if (result == DenseElementResult::Failure)
             return false;
         if (result == DenseElementResult::Incomplete) {
@@ -336,37 +332,31 @@ js::GetElementsWithAdder(JSContext* cx, HandleObject obj, HandleObject receiver,
     return true;
 }
 
-template <JSValueType Type>
-DenseElementResult
-GetBoxedOrUnboxedDenseElements(JSObject* aobj, uint32_t length, Value* vp)
+static bool
+GetDenseElements(NativeObject* aobj, uint32_t length, Value* vp)
 {
     MOZ_ASSERT(!ObjectMayHaveExtraIndexedProperties(aobj));
 
-    if (length > GetBoxedOrUnboxedInitializedLength<Type>(aobj))
-        return DenseElementResult::Incomplete;
+    if (length > aobj->getDenseInitializedLength())
+        return false;
 
     for (size_t i = 0; i < length; i++) {
-        vp[i] = GetBoxedOrUnboxedDenseElement<Type>(aobj, i);
+        vp[i] = aobj->getDenseElement(i);
 
         // No other indexed properties so hole => undefined.
         if (vp[i].isMagic(JS_ELEMENTS_HOLE))
             vp[i] = UndefinedValue();
     }
 
-    return DenseElementResult::Success;
+    return true;
 }
 
-DefineBoxedOrUnboxedFunctor3(GetBoxedOrUnboxedDenseElements,
-                             JSObject*, uint32_t, Value*);
-
 bool
 js::GetElements(JSContext* cx, HandleObject aobj, uint32_t length, Value* vp)
 {
     if (!ObjectMayHaveExtraIndexedProperties(aobj)) {
-        GetBoxedOrUnboxedDenseElementsFunctor functor(aobj, length, vp);
-        DenseElementResult result = CallBoxedOrUnboxedSpecialization(functor, aobj);
-        if (result != DenseElementResult::Incomplete)
-            return result == DenseElementResult::Success;
+        if (GetDenseElements(&aobj->as<NativeObject>(), length, vp))
+            return true;
     }
 
     if (aobj->is<ArgumentsObject>()) {
@@ -398,9 +388,9 @@ SetArrayElement(JSContext* cx, HandleObject obj, double index, HandleValue v)
 {
     MOZ_ASSERT(index >= 0);
 
-    if ((obj->is<ArrayObject>() || obj->is<UnboxedArrayObject>()) && !obj->isIndexed() && index <= UINT32_MAX) {
-        DenseElementResult result =
-            SetOrExtendAnyBoxedOrUnboxedDenseElements(cx, obj, uint32_t(index), v.address(), 1);
+    if (obj->is<ArrayObject>() && !obj->isIndexed() && index <= UINT32_MAX) {
+        NativeObject* nobj = &obj->as<NativeObject>();
+        DenseElementResult result = nobj->setOrExtendDenseElements(cx, uint32_t(index), v.address(), 1);
         if (result != DenseElementResult::Incomplete)
             return result == DenseElementResult::Success;
     }
@@ -520,24 +510,6 @@ struct ReverseIndexComparator
     }
 };
 
-bool
-js::CanonicalizeArrayLengthValue(JSContext* cx, HandleValue v, uint32_t* newLen)
-{
-    double d;
-
-    if (!ToUint32(cx, v, newLen))
-        return false;
-
-    if (!ToNumber(cx, v, &d))
-        return false;
-
-    if (d == *newLen)
-        return true;
-
-    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_ARRAY_LENGTH);
-    return false;
-}
-
 /* ES6 draft rev 34 (2015 Feb 20) 9.4.2.4 ArraySetLength */
 bool
 js::ArraySetLength(JSContext* cx, Handle<ArrayObject*> arr, HandleId id,
@@ -559,12 +531,22 @@ js::ArraySetLength(JSContext* cx, Handle<ArrayObject*> arr, HandleId id,
     } else {
         // Step 2 is irrelevant in our implementation.
 
-        // Steps 3-7.
-        MOZ_ASSERT_IF(attrs & JSPROP_IGNORE_VALUE, value.isUndefined());
-        if (!CanonicalizeArrayLengthValue(cx, value, &newLen))
+        // Step 3.
+        if (!ToUint32(cx, value, &newLen))
+            return false;
+
+        // Step 4.
+        double d;
+        if (!ToNumber(cx, value, &d))
             return false;
 
-        // Step 8 is irrelevant in our implementation.
+        // Step 5.
+        if (d != newLen) {
+            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_ARRAY_LENGTH);
+            return false;
+        }
+
+        // Steps 6-8 are irrelevant in our implementation.
     }
 
     // Steps 9-11.
@@ -823,7 +805,7 @@ array_addProperty(JSContext* cx, HandleObject obj, HandleId id, HandleValue v)
 static inline bool
 ObjectMayHaveExtraIndexedOwnProperties(JSObject* obj)
 {
-    return (!obj->isNative() && !obj->is<UnboxedArrayObject>()) ||
+    return !obj->isNative() ||
            obj->isIndexed() ||
            obj->is<TypedArrayObject>() ||
            ClassMayResolveId(*obj->runtimeFromAnyThread()->commonNames,
@@ -854,7 +836,7 @@ js::ObjectMayHaveExtraIndexedProperties(JSObject* obj)
 
         if (ObjectMayHaveExtraIndexedOwnProperties(obj))
             return true;
-        if (GetAnyBoxedOrUnboxedInitializedLength(obj) != 0)
+        if (obj->as<NativeObject>().getDenseInitializedLength() != 0)
             return true;
     } while (true);
 }
@@ -1064,31 +1046,32 @@ struct StringSeparatorOp
     }
 };
 
-template <typename SeparatorOp, JSValueType Type>
-static DenseElementResult
-ArrayJoinDenseKernel(JSContext* cx, SeparatorOp sepOp, HandleObject obj, uint32_t length,
+template <typename SeparatorOp>
+static bool
+ArrayJoinDenseKernel(JSContext* cx, SeparatorOp sepOp, HandleNativeObject obj, uint64_t length,
                      StringBuffer& sb, uint32_t* numProcessed)
 {
     // This loop handles all elements up to initializedLength. If
     // length > initLength we rely on the second loop to add the
     // other elements.
     MOZ_ASSERT(*numProcessed == 0);
-    uint32_t initLength = Min<uint32_t>(GetBoxedOrUnboxedInitializedLength<Type>(obj), length);
+    uint32_t initLength = Min<uint32_t>(obj->getDenseInitializedLength(),
+                                        length);
     while (*numProcessed < initLength) {
         if (!CheckForInterrupt(cx))
-            return DenseElementResult::Failure;
+            return false;
 
-        Value elem = GetBoxedOrUnboxedDenseElement<Type>(obj, *numProcessed);
+        Value elem = obj->as<NativeObject>().getDenseElement(*numProcessed);
 
         if (elem.isString()) {
             if (!sb.append(elem.toString()))
-                return DenseElementResult::Failure;
+                return false;
         } else if (elem.isNumber()) {
             if (!NumberValueToStringBuffer(cx, elem, sb))
-                return DenseElementResult::Failure;
+                return false;
         } else if (elem.isBoolean()) {
             if (!BooleanToStringBuffer(elem.toBoolean(), sb))
-                return DenseElementResult::Failure;
+                return false;
         } else if (elem.isObject() || elem.isSymbol()) {
             /*
              * Object stringifying could modify the initialized length or make
@@ -1104,33 +1087,13 @@ ArrayJoinDenseKernel(JSContext* cx, SeparatorOp sepOp, HandleObject obj, uint32_
         }
 
         if (++(*numProcessed) != length && !sepOp(cx, sb))
-            return DenseElementResult::Failure;
+            return false;
     }
 
-    return DenseElementResult::Incomplete;
+    return true;
 }
 
 template <typename SeparatorOp>
-struct ArrayJoinDenseKernelFunctor {
-    JSContext* cx;
-    SeparatorOp sepOp;
-    HandleObject obj;
-    uint32_t length;
-    StringBuffer& sb;
-    uint32_t* numProcessed;
-
-    ArrayJoinDenseKernelFunctor(JSContext* cx, SeparatorOp sepOp, HandleObject obj,
-                                uint32_t length, StringBuffer& sb, uint32_t* numProcessed)
-      : cx(cx), sepOp(sepOp), obj(obj), length(length), sb(sb), numProcessed(numProcessed)
-    {}
-
-    template <JSValueType Type>
-    DenseElementResult operator()() {
-        return ArrayJoinDenseKernel<SeparatorOp, Type>(cx, sepOp, obj, length, sb, numProcessed);
-    }
-};
-
-template <typename SeparatorOp>
 static bool
 ArrayJoinKernel(JSContext* cx, SeparatorOp sepOp, HandleObject obj, uint32_t length,
                StringBuffer& sb)
@@ -1138,10 +1101,10 @@ ArrayJoinKernel(JSContext* cx, SeparatorOp sepOp, HandleObject obj, uint32_t len
     uint32_t i = 0;
 
     if (!ObjectMayHaveExtraIndexedProperties(obj)) {
-        ArrayJoinDenseKernelFunctor<SeparatorOp> functor(cx, sepOp, obj, length, sb, &i);
-        DenseElementResult result = CallBoxedOrUnboxedSpecialization(functor, obj);
-        if (result == DenseElementResult::Failure)
+        if (!ArrayJoinDenseKernel<SeparatorOp>(cx, sepOp, obj.as<NativeObject>(), length, sb, &i))
+        {
             return false;
+        }
     }
 
     if (i != length) {
@@ -1212,11 +1175,14 @@ js::array_join(JSContext* cx, unsigned argc, Value* vp)
     // An optimized version of a special case of steps 7-11: when length==1 and
     // the 0th element is a string, ToString() of that element is a no-op and
     // so it can be immediately returned as the result.
-    if (length == 1 && GetAnyBoxedOrUnboxedInitializedLength(obj) == 1) {
-        Value elem0 = GetAnyBoxedOrUnboxedDenseElement(obj, 0);
-        if (elem0.isString()) {
-            args.rval().set(elem0);
-            return true;
+    if (length == 1 && obj->isNative()) {
+        NativeObject* nobj = &obj->as<NativeObject>();
+        if (nobj->getDenseInitializedLength() == 1) {
+            Value elem0 = nobj->getDenseElement(0);
+            if (elem0.isString()) {
+                args.rval().set(elem0);
+                return true;
+            }
         }
     }
 
@@ -1259,7 +1225,7 @@ js::array_join(JSContext* cx, unsigned argc, Value* vp)
     }
 
     // Step 11
-    JSString *str = sb.finishString();
+    JSString* str = sb.finishString();
     if (!str)
         return false;
 
@@ -1288,10 +1254,6 @@ array_toLocaleString(JSContext* cx, unsigned argc, Value* vp)
         args.rval().setString(cx->names().empty);
         return true;
     }
-    if (obj->is<UnboxedArrayObject>() && obj->as<UnboxedArrayObject>().length() == 0) {
-        args.rval().setString(cx->names().empty);
-        return true;
-    }
 
     AutoCycleDetector detector(cx, obj);
     if (!detector.init())
@@ -1328,8 +1290,9 @@ InitArrayElements(JSContext* cx, HandleObject obj, uint32_t start,
         return false;
 
     if (!ObjectMayHaveExtraIndexedProperties(obj)) {
-        DenseElementResult result =
-            SetOrExtendAnyBoxedOrUnboxedDenseElements(cx, obj, start, vector, count, updateTypes);
+        NativeObject* nobj = &obj->as<NativeObject>();
+        DenseElementResult result = nobj->setOrExtendDenseElements(cx, uint32_t(start), vector,
+                                                                   count, updateTypes);
         if (result != DenseElementResult::Incomplete)
             return result == DenseElementResult::Success;
     }
@@ -1363,54 +1326,45 @@ InitArrayElements(JSContext* cx, HandleObject obj, uint32_t start,
     return true;
 }
 
-template <JSValueType Type>
-DenseElementResult
-ArrayReverseDenseKernel(JSContext* cx, HandleObject obj, uint32_t length)
+static DenseElementResult
+ArrayReverseDenseKernel(JSContext* cx, HandleNativeObject obj, uint32_t length)
 {
     /* An empty array or an array with no elements is already reversed. */
-    if (length == 0 || GetBoxedOrUnboxedInitializedLength<Type>(obj) == 0)
+    if (length == 0 || obj->getDenseInitializedLength() == 0)
         return DenseElementResult::Success;
 
-    if (Type == JSVAL_TYPE_MAGIC) {
-        if (obj->as<NativeObject>().denseElementsAreFrozen())
-            return DenseElementResult::Incomplete;
+    if (obj->denseElementsAreFrozen())
+        return DenseElementResult::Incomplete;
 
-        /*
-         * It's actually surprisingly complicated to reverse an array due to the
-         * orthogonality of array length and array capacity while handling
-         * leading and trailing holes correctly.  Reversing seems less likely to
-         * be a common operation than other array mass-mutation methods, so for
-         * now just take a probably-small memory hit (in the absence of too many
-         * holes in the array at its start) and ensure that the capacity is
-         * sufficient to hold all the elements in the array if it were full.
-         */
-        DenseElementResult result = obj->as<NativeObject>().ensureDenseElements(cx, length, 0);
-        if (result != DenseElementResult::Success)
-            return result;
+    /*
+     * It's actually surprisingly complicated to reverse an array due to the
+     * orthogonality of array length and array capacity while handling
+     * leading and trailing holes correctly.  Reversing seems less likely to
+     * be a common operation than other array mass-mutation methods, so for
+     * now just take a probably-small memory hit (in the absence of too many
+     * holes in the array at its start) and ensure that the capacity is
+     * sufficient to hold all the elements in the array if it were full.
+     */
+    DenseElementResult result = obj->ensureDenseElements(cx, length, 0);
+    if (result != DenseElementResult::Success)
+        return result;
 
-        /* Fill out the array's initialized length to its proper length. */
-        obj->as<NativeObject>().ensureDenseInitializedLength(cx, length, 0);
-    } else {
-        // Unboxed arrays can only be reversed here if their initialized length
-        // matches their actual length. Otherwise the reversal will place holes
-        // at the beginning of the array, which we don't support.
-        if (length != obj->as<UnboxedArrayObject>().initializedLength())
-            return DenseElementResult::Incomplete;
-    }
+    /* Fill out the array's initialized length to its proper length. */
+    obj->ensureDenseInitializedLength(cx, length, 0);
 
     RootedValue origlo(cx), orighi(cx);
 
     uint32_t lo = 0, hi = length - 1;
     for (; lo < hi; lo++, hi--) {
-        origlo = GetBoxedOrUnboxedDenseElement<Type>(obj, lo);
-        orighi = GetBoxedOrUnboxedDenseElement<Type>(obj, hi);
-        SetBoxedOrUnboxedDenseElementNoTypeChange<Type>(obj, lo, orighi);
+        origlo = obj->getDenseElement(lo);
+        orighi = obj->getDenseElement(hi);
+        obj->setDenseElement(lo, orighi);
         if (orighi.isMagic(JS_ELEMENTS_HOLE) &&
             !SuppressDeletedProperty(cx, obj, INT_TO_JSID(lo)))
         {
             return DenseElementResult::Failure;
         }
-        SetBoxedOrUnboxedDenseElementNoTypeChange<Type>(obj, hi, origlo);
+        obj->setDenseElement(hi, origlo);
         if (origlo.isMagic(JS_ELEMENTS_HOLE) &&
             !SuppressDeletedProperty(cx, obj, INT_TO_JSID(hi)))
         {
@@ -1421,9 +1375,6 @@ ArrayReverseDenseKernel(JSContext* cx, HandleObject obj, uint32_t length)
     return DenseElementResult::Success;
 }
 
-DefineBoxedOrUnboxedFunctor3(ArrayReverseDenseKernel,
-                             JSContext*, HandleObject, uint32_t);
-
 bool
 js::array_reverse(JSContext* cx, unsigned argc, Value* vp)
 {
@@ -1438,8 +1389,8 @@ js::array_reverse(JSContext* cx, unsigned argc, Value* vp)
         return false;
 
     if (!ObjectMayHaveExtraIndexedProperties(obj)) {
-        ArrayReverseDenseKernelFunctor functor(cx, obj, len);
-        DenseElementResult result = CallBoxedOrUnboxedSpecialization(functor, obj);
+        DenseElementResult result =
+            ArrayReverseDenseKernel(cx, obj.as<NativeObject>(), uint32_t(len));
         if (result != DenseElementResult::Incomplete) {
             /*
              * Per ECMA-262, don't update the length of the array, even if the new
@@ -2082,8 +2033,8 @@ js::array_push(JSContext* cx, unsigned argc, Value* vp)
 
     if (!ObjectMayHaveExtraIndexedProperties(obj)) {
         DenseElementResult result =
-            SetOrExtendAnyBoxedOrUnboxedDenseElements(cx, obj, length,
-                                                      args.array(), args.length());
+            obj->as<NativeObject>().setOrExtendDenseElements(cx, uint32_t(length),
+                                                             args.array(), args.length());
         if (result != DenseElementResult::Incomplete) {
             if (result == DenseElementResult::Failure)
                 return false;
@@ -2091,14 +2042,8 @@ js::array_push(JSContext* cx, unsigned argc, Value* vp)
             uint32_t newlength = length + args.length();
             args.rval().setNumber(newlength);
 
-            // SetOrExtendAnyBoxedOrUnboxedDenseElements takes care of updating the
-            // length for boxed and unboxed arrays. Handle updates to the length of
-            // non-arrays here.
-            bool isArray;
-            if (!IsArray(cx, obj, &isArray))
-                return false;
-
-            if (!isArray)
+            // Handle updates to the length of non-arrays here.
+            if (!obj->is<ArrayObject>())
                 return SetLengthProperty(cx, obj, newlength);
 
             return true;
@@ -2154,42 +2099,46 @@ js::array_pop(JSContext* cx, unsigned argc, Value* vp)
     return SetLengthProperty(cx, obj, index);
 }
 
-template <JSValueType Type>
-static inline DenseElementResult
-ShiftMoveBoxedOrUnboxedDenseElements(JSObject* obj)
+void
+js::ArrayShiftMoveElements(NativeObject* obj)
 {
-    MOZ_ASSERT(HasBoxedOrUnboxedDenseElements<Type>(obj));
+    MOZ_ASSERT_IF(obj->is<ArrayObject>(), obj->as<ArrayObject>().lengthIsWritable());
+
+    size_t initlen = obj->getDenseInitializedLength();
+    MOZ_ASSERT(initlen > 0);
 
     /*
      * At this point the length and initialized length have already been
      * decremented and the result fetched, so just shift the array elements
      * themselves.
      */
-    size_t initlen = GetBoxedOrUnboxedInitializedLength<Type>(obj);
-    if (Type == JSVAL_TYPE_MAGIC) {
-        obj->as<NativeObject>().moveDenseElementsNoPreBarrier(0, 1, initlen);
-    } else {
-        uint8_t* data = obj->as<UnboxedArrayObject>().elements();
-        size_t elementSize = UnboxedTypeSize(Type);
-        memmove(data, data + elementSize, initlen * elementSize);
-    }
-
-    return DenseElementResult::Success;
+    obj->moveDenseElementsNoPreBarrier(0, 1, initlen);
 }
 
-DefineBoxedOrUnboxedFunctor1(ShiftMoveBoxedOrUnboxedDenseElements, JSObject*);
+static inline void
+SetInitializedLength(JSContext* cx, NativeObject* obj, size_t initlen)
+{
+    size_t oldInitlen = obj->getDenseInitializedLength();
+    obj->setDenseInitializedLength(initlen);
+    if (initlen < oldInitlen)
+        obj->shrinkElements(cx, initlen);
+}
 
-void
-js::ArrayShiftMoveElements(JSObject* obj)
+static DenseElementResult
+MoveDenseElements(JSContext* cx, NativeObject* obj, uint32_t dstStart, uint32_t srcStart,
+                  uint32_t length)
 {
-    MOZ_ASSERT_IF(obj->is<ArrayObject>(), obj->as<ArrayObject>().lengthIsWritable());
+    if (obj->denseElementsAreFrozen())
+        return DenseElementResult::Incomplete;
 
-    ShiftMoveBoxedOrUnboxedDenseElementsFunctor functor(obj);
-    JS_ALWAYS_TRUE(CallBoxedOrUnboxedSpecialization(functor, obj) == DenseElementResult::Success);
+    if (!obj->maybeCopyElementsForWrite(cx))
+        return DenseElementResult::Failure;
+    obj->moveDenseElements(dstStart, srcStart, length);
+
+    return DenseElementResult::Success;
 }
 
-template <JSValueType Type>
-DenseElementResult
+static DenseElementResult
 ArrayShiftDenseKernel(JSContext* cx, HandleObject obj, MutableHandleValue rval)
 {
     if (ObjectMayHaveExtraIndexedProperties(obj))
@@ -2202,25 +2151,22 @@ ArrayShiftDenseKernel(JSContext* cx, HandleObject obj, MutableHandleValue rval)
     if (MOZ_UNLIKELY(group->hasAllFlags(OBJECT_FLAG_ITERATED)))
         return DenseElementResult::Incomplete;
 
-    size_t initlen = GetBoxedOrUnboxedInitializedLength<Type>(obj);
+    size_t initlen = obj->as<NativeObject>().getDenseInitializedLength();
     if (initlen == 0)
         return DenseElementResult::Incomplete;
 
-    rval.set(GetBoxedOrUnboxedDenseElement<Type>(obj, 0));
+    rval.set(obj->as<NativeObject>().getDenseElement(0));
     if (rval.isMagic(JS_ELEMENTS_HOLE))
         rval.setUndefined();
 
-    DenseElementResult result = MoveBoxedOrUnboxedDenseElements<Type>(cx, obj, 0, 1, initlen - 1);
+    DenseElementResult result = MoveDenseElements(cx, &obj->as<NativeObject>(), 0, 1, initlen - 1);
     if (result != DenseElementResult::Success)
         return result;
 
-    SetBoxedOrUnboxedInitializedLength<Type>(cx, obj, initlen - 1);
+    SetInitializedLength(cx, obj.as<NativeObject>(), initlen - 1);
     return DenseElementResult::Success;
 }
 
-DefineBoxedOrUnboxedFunctor3(ArrayShiftDenseKernel,
-                             JSContext*, HandleObject, MutableHandleValue);
-
 /* ES5 15.4.4.9 */
 bool
 js::array_shift(JSContext* cx, unsigned argc, Value* vp)
@@ -2252,8 +2198,7 @@ js::array_shift(JSContext* cx, unsigned argc, Value* vp)
     uint32_t newlen = len - 1;
 
     /* Fast paths. */
-    ArrayShiftDenseKernelFunctor functor(cx, obj, args.rval());
-    DenseElementResult result = CallBoxedOrUnboxedSpecialization(functor, obj);
+    DenseElementResult result = ArrayShiftDenseKernel(cx, obj, args.rval());
     if (result != DenseElementResult::Incomplete) {
         if (result == DenseElementResult::Failure)
             return false;
@@ -2307,9 +2252,6 @@ js::array_unshift(JSContext* cx, unsigned argc, Value* vp)
     if (args.length() > 0) {
         /* Slide up the array to make room for all args at the bottom. */
         if (length > 0) {
-            // Only include a fast path for boxed arrays. Unboxed arrays can'nt
-            // be optimized here because unshifting temporarily places holes at
-            // the start of the array.
             bool optimized = false;
             do {
                 if (!obj->is<ArrayObject>())
@@ -2369,10 +2311,10 @@ js::array_unshift(JSContext* cx, unsigned argc, Value* vp)
 }
 
 /*
- * Returns true if this is a dense or unboxed array whose |count| properties
- * starting from |startingIndex| may be accessed (get, set, delete) directly
- * through its contiguous vector of elements without fear of getters, setters,
- * etc. along the prototype chain, or of enumerators requiring notification of
+ * Returns true if this is a dense array whose properties ending at |endIndex|
+ * (exclusive) may be accessed (get, set, delete) directly through its
+ * contiguous vector of elements without fear of getters, setters, etc. along
+ * the prototype chain, or of enumerators requiring notification of
  * modifications.
  */
 static inline bool
@@ -2383,11 +2325,11 @@ CanOptimizeForDenseStorage(HandleObject arr, uint32_t startingIndex, uint32_t co
         return false;
 
     /* There's no optimizing possible if it's not an array. */
-    if (!arr->is<ArrayObject>() && !arr->is<UnboxedArrayObject>())
+    if (!arr->is<ArrayObject>())
         return false;
 
     /* If it's a frozen array, always pick the slow path */
-    if (arr->is<ArrayObject>() && arr->as<ArrayObject>().denseElementsAreFrozen())
+    if (arr->as<ArrayObject>().denseElementsAreFrozen())
         return false;
 
     /*
@@ -2419,7 +2361,23 @@ CanOptimizeForDenseStorage(HandleObject arr, uint32_t startingIndex, uint32_t co
      * is subsumed by the initializedLength comparison.)
      */
     return !ObjectMayHaveExtraIndexedProperties(arr) &&
-           startingIndex + count <= GetAnyBoxedOrUnboxedInitializedLength(arr);
+           startingIndex + count <= arr->as<NativeObject>().getDenseInitializedLength();
+}
+
+static inline DenseElementResult
+CopyDenseElements(JSContext* cx, NativeObject* dst, NativeObject* src,
+                      uint32_t dstStart, uint32_t srcStart, uint32_t length)
+{
+    MOZ_ASSERT(dst->getDenseInitializedLength() == dstStart);
+    MOZ_ASSERT(src->getDenseInitializedLength() >= srcStart + length);
+    MOZ_ASSERT(dst->getDenseCapacity() >= dstStart + length);
+
+    dst->setDenseInitializedLength(dstStart + length);
+
+    const Value* vp = src->getDenseElements() + srcStart;
+    dst->initDenseElements(dstStart, vp, length);
+
+    return DenseElementResult::Success;
 }
 
 /* ES 2016 draft Mar 25, 2016 22.1.3.26. */
@@ -2520,7 +2478,9 @@ js::array_splice_impl(JSContext* cx, unsigned argc, Value* vp, bool returnValueI
 
                 /* Steps 10-11. */
                 DebugOnly<DenseElementResult> result =
-                    CopyAnyBoxedOrUnboxedDenseElements(cx, arr, obj, 0, actualStart, actualDeleteCount);
+                    CopyDenseElements(cx, &arr->as<NativeObject>(), 
+                                      &obj->as<NativeObject>(), 0, 
+                                      actualStart, actualDeleteCount);
                 MOZ_ASSERT(result.value == DenseElementResult::Success);
 
                 /* Step 12 (implicit). */
@@ -2557,14 +2517,13 @@ js::array_splice_impl(JSContext* cx, unsigned argc, Value* vp, bool returnValueI
         if (CanOptimizeForDenseStorage(obj, 0, len, cx)) {
             /* Steps 15.a-b. */
             DenseElementResult result =
-                MoveAnyBoxedOrUnboxedDenseElements(cx, obj, targetIndex, sourceIndex,
-                                                   len - sourceIndex);
+                MoveDenseElements(cx, &obj->as<NativeObject>(), targetIndex, sourceIndex, len - sourceIndex);
             MOZ_ASSERT(result != DenseElementResult::Incomplete);
             if (result == DenseElementResult::Failure)
                 return false;
 
             /* Steps 15.c-d. */
-            SetAnyBoxedOrUnboxedInitializedLength(cx, obj, finalLength);
+            SetInitializedLength(cx, obj.as<NativeObject>(), finalLength);
         } else {
             /*
              * This is all very slow if the length is very large. We don't yet
@@ -2644,15 +2603,15 @@ js::array_splice_impl(JSContext* cx, unsigned argc, Value* vp, bool returnValueI
 
         if (CanOptimizeForDenseStorage(obj, len, itemCount - actualDeleteCount, cx)) {
             DenseElementResult result =
-                MoveAnyBoxedOrUnboxedDenseElements(cx, obj, actualStart + itemCount,
-                                                   actualStart + actualDeleteCount,
-                                                   len - (actualStart + actualDeleteCount));
+                MoveDenseElements(cx, &obj->as<NativeObject>(), actualStart + itemCount,
+                                  actualStart + actualDeleteCount,
+                                  len - (actualStart + actualDeleteCount));
             MOZ_ASSERT(result != DenseElementResult::Incomplete);
             if (result == DenseElementResult::Failure)
                 return false;
 
             /* Steps 16.a-b. */
-            SetAnyBoxedOrUnboxedInitializedLength(cx, obj, len + itemCount - actualDeleteCount);
+            SetInitializedLength(cx, obj.as<NativeObject>(), len + itemCount - actualDeleteCount);
         } else {
             RootedValue fromValue(cx);
             for (double k = len - actualDeleteCount; k > actualStart; k--) {
@@ -2824,7 +2783,7 @@ SliceSlowly(JSContext* cx, HandleObject obj, HandleObject receiver,
 }
 
 static bool
-SliceSparse(JSContext* cx, HandleObject obj, uint32_t begin, uint32_t end, HandleObject result)
+SliceSparse(JSContext* cx, HandleObject obj, uint32_t begin, uint32_t end, HandleArrayObject result)
 {
     MOZ_ASSERT(begin <= end);
 
@@ -2874,26 +2833,28 @@ ArraySliceOrdinary(JSContext* cx, HandleObject obj, uint32_t length, uint32_t be
         begin = end;
 
     if (!ObjectMayHaveExtraIndexedProperties(obj)) {
-        size_t initlen = GetAnyBoxedOrUnboxedInitializedLength(obj);
+        size_t initlen = obj->as<NativeObject>().getDenseInitializedLength();
         size_t count = 0;
         if (initlen > begin)
             count = Min<size_t>(initlen - begin, end - begin);
 
-        RootedObject narr(cx, NewFullyAllocatedArrayTryReuseGroup(cx, obj, count));
+        RootedArrayObject narr(cx, NewFullyAllocatedArrayTryReuseGroup(cx, obj, count));
         if (!narr)
             return false;
-        SetAnyBoxedOrUnboxedArrayLength(cx, narr, end - begin);
+
+        MOZ_ASSERT(count >= narr->as<ArrayObject>().length());
+        narr->as<ArrayObject>().setLength(cx, count);
 
         if (count) {
             DebugOnly<DenseElementResult> result =
-                CopyAnyBoxedOrUnboxedDenseElements(cx, narr, obj, 0, begin, count);
+                CopyDenseElements(cx, &narr->as<NativeObject>(), &obj->as<NativeObject>(), 0, begin, count);
             MOZ_ASSERT(result.value == DenseElementResult::Success);
         }
         arr.set(narr);
         return true;
     }
 
-    RootedObject narr(cx, NewPartlyAllocatedArrayTryReuseGroup(cx, obj, end - begin));
+    RootedArrayObject narr(cx, NewPartlyAllocatedArrayTryReuseGroup(cx, obj, end - begin));
     if (!narr)
         return false;
 
@@ -3010,11 +2971,10 @@ js::array_slice(JSContext* cx, unsigned argc, Value* vp)
     return true;
 }
 
-template <JSValueType Type>
-DenseElementResult
-ArraySliceDenseKernel(JSContext* cx, JSObject* obj, int32_t beginArg, int32_t endArg, JSObject* result)
+static bool
+ArraySliceDenseKernel(JSContext* cx, ArrayObject* arr, int32_t beginArg, int32_t endArg, ArrayObject* result)
 {
-    int32_t length = GetAnyBoxedOrUnboxedArrayLength(obj);
+    int32_t length = arr->length();
 
     uint32_t begin = NormalizeSliceTerm(beginArg, length);
     uint32_t end = NormalizeSliceTerm(endArg, length);
@@ -3022,33 +2982,33 @@ ArraySliceDenseKernel(JSContext* cx, JSObject* obj, int32_t beginArg, int32_t en
     if (begin > end)
         begin = end;
 
-    size_t initlen = GetBoxedOrUnboxedInitializedLength<Type>(obj);
+    size_t initlen = arr->getDenseInitializedLength();
+    size_t count = Min<size_t>(initlen - begin, end - begin);
     if (initlen > begin) {
-        size_t count = Min<size_t>(initlen - begin, end - begin);
         if (count) {
-            DenseElementResult rv = EnsureBoxedOrUnboxedDenseElements<Type>(cx, result, count);
-            if (rv != DenseElementResult::Success)
-                return rv;
-            CopyBoxedOrUnboxedDenseElements<Type, Type>(cx, result, obj, 0, begin, count);
+            if (!result->ensureElements(cx, count))
+                return false;
+            CopyDenseElements(cx, &result->as<NativeObject>(), &arr->as<NativeObject>(), 0, begin, count);
         }
     }
 
-    SetAnyBoxedOrUnboxedArrayLength(cx, result, end - begin);
-    return DenseElementResult::Success;
-}
+    MOZ_ASSERT(count >= result->length());
+    result->setLength(cx, count);
 
-DefineBoxedOrUnboxedFunctor5(ArraySliceDenseKernel,
-                             JSContext*, JSObject*, int32_t, int32_t, JSObject*);
+    return true;
+}
 
 JSObject*
 js::array_slice_dense(JSContext* cx, HandleObject obj, int32_t begin, int32_t end,
                       HandleObject result)
 {
     if (result && IsArraySpecies(cx, obj)) {
-        ArraySliceDenseKernelFunctor functor(cx, obj, begin, end, result);
-        DenseElementResult rv = CallBoxedOrUnboxedSpecialization(functor, result);
-        MOZ_ASSERT(rv != DenseElementResult::Incomplete);
-        return rv == DenseElementResult::Success ? result : nullptr;
+        if (!ArraySliceDenseKernel(cx, &obj->as<ArrayObject>(), begin, end,
+                                   &result->as<ArrayObject>()))
+        {
+            return nullptr;
+        }
+        return result;
     }
 
     // Slower path if the JIT wasn't able to allocate an object inline.
@@ -3079,7 +3039,7 @@ array_isArray(JSContext* cx, unsigned argc, Value* vp)
 static bool
 ArrayFromCallArgs(JSContext* cx, CallArgs& args, HandleObject proto = nullptr)
 {
-    JSObject* obj = NewCopiedArrayForCallingAllocationSite(cx, args.array(), args.length(), proto);
+    ArrayObject* obj = NewCopiedArrayForCallingAllocationSite(cx, args.array(), args.length(), proto);
     if (!obj)
         return false;
 
@@ -3169,6 +3129,11 @@ static const JSFunctionSpec array_methods[] = {
 
     /* ES7 additions */
     JS_SELF_HOSTED_FN("includes",    "ArrayIncludes",    2,0),
+    
+    /* ES2019 additions */
+    JS_SELF_HOSTED_FN("flat",        "ArrayFlat",        0,0),
+    JS_SELF_HOSTED_FN("flatMap",     "ArrayFlatMap",     1,0),
+    
     JS_FS_END
 };
 
@@ -3239,7 +3204,7 @@ ArrayConstructorImpl(JSContext* cx, CallArgs& args, bool isConstructor)
         }
     }
 
-    JSObject* obj = NewPartlyAllocatedArrayForCallingAllocationSite(cx, length, proto);
+    ArrayObject* obj = NewPartlyAllocatedArrayForCallingAllocationSite(cx, length, proto);
     if (!obj)
         return false;
 
@@ -3265,7 +3230,7 @@ js::array_construct(JSContext* cx, unsigned argc, Value* vp)
     return ArrayConstructorImpl(cx, args, /* isConstructor = */ false);
 }
 
-JSObject*
+ArrayObject*
 js::ArrayConstructorOneArg(JSContext* cx, HandleObjectGroup group, int32_t lengthInt)
 {
     if (lengthInt < 0) {
@@ -3333,6 +3298,8 @@ array_proto_finish(JSContext* cx, JS::HandleObject ctor, JS::HandleObject proto)
         !DefineProperty(cx, unscopables, cx->names().fill, value) ||
         !DefineProperty(cx, unscopables, cx->names().find, value) ||
         !DefineProperty(cx, unscopables, cx->names().findIndex, value) ||
+        !DefineProperty(cx, unscopables, cx->names().flat, value) ||
+        !DefineProperty(cx, unscopables, cx->names().flatMap, value) ||
         !DefineProperty(cx, unscopables, cx->names().includes, value) ||
         !DefineProperty(cx, unscopables, cx->names().keys, value) ||
         !DefineProperty(cx, unscopables, cx->names().values, value))
@@ -3558,7 +3525,7 @@ js::NewDenseFullyAllocatedArrayWithTemplate(JSContext* cx, uint32_t length, JSOb
     return arr;
 }
 
-JSObject*
+ArrayObject*
 js::NewDenseCopyOnWriteArray(JSContext* cx, HandleArrayObject templateObject, gc::InitialHeap heap)
 {
     MOZ_ASSERT(!gc::IsInsideNursery(templateObject));
@@ -3571,30 +3538,21 @@ js::NewDenseCopyOnWriteArray(JSContext* cx, HandleArrayObject templateObject, gc
     return arr;
 }
 
-// Return a new boxed or unboxed array with the specified length and allocated
-// capacity (up to maxLength), using the specified group if possible. If the
-// specified group cannot be used, ensure that the created array at least has
-// the given [[Prototype]].
+// Return a new array with the specified length and allocated capacity (up to
+// maxLength), using the specified group if possible. If the specified group
+// cannot be used, ensure that the created array at least has the given
+// [[Prototype]].
 template <uint32_t maxLength>
-static inline JSObject*
+static inline ArrayObject*
 NewArrayTryUseGroup(ExclusiveContext* cx, HandleObjectGroup group, size_t length,
                     NewObjectKind newKind = GenericObject)
 {
     MOZ_ASSERT(newKind != SingletonObject);
 
-    if (group->maybePreliminaryObjects())
-        group->maybePreliminaryObjects()->maybeAnalyze(cx, group);
-
-    if (group->shouldPreTenure() || group->maybePreliminaryObjects())
+    if (group->shouldPreTenure())
         newKind = TenuredObject;
 
     RootedObject proto(cx, group->proto().toObject());
-    if (group->maybeUnboxedLayout()) {
-        if (length > UnboxedArrayObject::MaximumCapacity)
-            return NewArray<maxLength>(cx, length, proto, newKind);
-        return UnboxedArrayObject::create(cx, group, length, newKind, maxLength);
-    }
-
     ArrayObject* res = NewArray<maxLength>(cx, length, proto, newKind);
     if (!res)
         return nullptr;
@@ -3606,20 +3564,17 @@ NewArrayTryUseGroup(ExclusiveContext* cx, HandleObjectGroup group, size_t length
     if (res->length() > INT32_MAX)
         res->setLength(cx, res->length());
 
-    if (PreliminaryObjectArray* preliminaryObjects = group->maybePreliminaryObjects())
-        preliminaryObjects->registerNewObject(res);
-
     return res;
 }
 
-JSObject*
+ArrayObject*
 js::NewFullyAllocatedArrayTryUseGroup(ExclusiveContext* cx, HandleObjectGroup group, size_t length,
                                       NewObjectKind newKind)
 {
     return NewArrayTryUseGroup<UINT32_MAX>(cx, group, length, newKind);
 }
 
-JSObject*
+ArrayObject*
 js::NewPartlyAllocatedArrayTryUseGroup(ExclusiveContext* cx, HandleObjectGroup group, size_t length)
 {
     return NewArrayTryUseGroup<ArrayObject::EagerAllocationMaxLength>(cx, group, length);
@@ -3628,16 +3583,13 @@ js::NewPartlyAllocatedArrayTryUseGroup(ExclusiveContext* cx, HandleObjectGroup g
 // Return a new array with the default prototype and specified allocated
 // capacity and length. If possible, try to reuse the group of the input
 // object. The resulting array will either reuse the input object's group or
-// will have unknown property types. Additionally, the result will have the
-// same boxed/unboxed elements representation as the input object, unless
-// |length| is larger than the input object's initialized length (in which case
-// UnboxedArrayObject::MaximumCapacity might be exceeded).
+// will have unknown property types.
 template <uint32_t maxLength>
-static inline JSObject*
+static inline ArrayObject*
 NewArrayTryReuseGroup(JSContext* cx, JSObject* obj, size_t length,
                       NewObjectKind newKind = GenericObject)
 {
-    if (!obj->is<ArrayObject>() && !obj->is<UnboxedArrayObject>())
+    if (!obj->is<ArrayObject>())
         return NewArray<maxLength>(cx, length, nullptr, newKind);
 
     if (obj->staticPrototype() != cx->global()->maybeGetArrayPrototype())
@@ -3650,20 +3602,20 @@ NewArrayTryReuseGroup(JSContext* cx, JSObject* obj, size_t length,
     return NewArrayTryUseGroup<maxLength>(cx, group, length, newKind);
 }
 
-JSObject*
+ArrayObject*
 js::NewFullyAllocatedArrayTryReuseGroup(JSContext* cx, JSObject* obj, size_t length,
                                         NewObjectKind newKind)
 {
     return NewArrayTryReuseGroup<UINT32_MAX>(cx, obj, length, newKind);
 }
 
-JSObject*
+ArrayObject*
 js::NewPartlyAllocatedArrayTryReuseGroup(JSContext* cx, JSObject* obj, size_t length)
 {
     return NewArrayTryReuseGroup<ArrayObject::EagerAllocationMaxLength>(cx, obj, length);
 }
 
-JSObject*
+ArrayObject*
 js::NewFullyAllocatedArrayForCallingAllocationSite(JSContext* cx, size_t length,
                                                    NewObjectKind newKind)
 {
@@ -3673,7 +3625,7 @@ js::NewFullyAllocatedArrayForCallingAllocationSite(JSContext* cx, size_t length,
     return NewArrayTryUseGroup<UINT32_MAX>(cx, group, length, newKind);
 }
 
-JSObject*
+ArrayObject*
 js::NewPartlyAllocatedArrayForCallingAllocationSite(JSContext* cx, size_t length, HandleObject proto)
 {
     RootedObjectGroup group(cx, ObjectGroup::callingAllocationSiteGroup(cx, JSProto_Array, proto));
@@ -3682,68 +3634,23 @@ js::NewPartlyAllocatedArrayForCallingAllocationSite(JSContext* cx, size_t length
     return NewArrayTryUseGroup<ArrayObject::EagerAllocationMaxLength>(cx, group, length);
 }
 
-bool
-js::MaybeAnalyzeBeforeCreatingLargeArray(ExclusiveContext* cx, HandleObjectGroup group,
-                                         const Value* vp, size_t length)
-{
-    static const size_t EagerPreliminaryObjectAnalysisThreshold = 800;
-
-    // Force analysis to see if an unboxed array can be used when making a
-    // sufficiently large array, to avoid excessive analysis and copying later
-    // on. If this is the first array of its group that is being created, first
-    // make a dummy array with the initial elements of the array we are about
-    // to make, so there is some basis for the unboxed array analysis.
-    if (length > EagerPreliminaryObjectAnalysisThreshold) {
-        if (PreliminaryObjectArrayWithTemplate* objects = group->maybePreliminaryObjects()) {
-            if (objects->empty()) {
-                size_t nlength = Min<size_t>(length, 100);
-                JSObject* obj = NewFullyAllocatedArrayTryUseGroup(cx, group, nlength);
-                if (!obj)
-                    return false;
-                DebugOnly<DenseElementResult> result =
-                    SetOrExtendAnyBoxedOrUnboxedDenseElements(cx, obj, 0, vp, nlength,
-                                                              ShouldUpdateTypes::Update);
-                MOZ_ASSERT(result.value == DenseElementResult::Success);
-            }
-            objects->maybeAnalyze(cx, group, /* forceAnalyze = */ true);
-        }
-    }
-    return true;
-}
-
-JSObject*
+ArrayObject*
 js::NewCopiedArrayTryUseGroup(ExclusiveContext* cx, HandleObjectGroup group,
                               const Value* vp, size_t length, NewObjectKind newKind,
                               ShouldUpdateTypes updateTypes)
 {
-    if (!MaybeAnalyzeBeforeCreatingLargeArray(cx, group, vp, length))
-        return nullptr;
-
-    JSObject* obj = NewFullyAllocatedArrayTryUseGroup(cx, group, length, newKind);
+    ArrayObject* obj = NewFullyAllocatedArrayTryUseGroup(cx, group, length, newKind);
     if (!obj)
         return nullptr;
 
-    DenseElementResult result =
-        SetOrExtendAnyBoxedOrUnboxedDenseElements(cx, obj, 0, vp, length, updateTypes);
-    if (result == DenseElementResult::Failure)
-        return nullptr;
-    if (result == DenseElementResult::Success)
-        return obj;
-
-    MOZ_ASSERT(obj->is<UnboxedArrayObject>());
-    if (!UnboxedArrayObject::convertToNative(cx->asJSContext(), obj))
-        return nullptr;
-
-    result = SetOrExtendBoxedOrUnboxedDenseElements<JSVAL_TYPE_MAGIC>(cx, obj, 0, vp, length,
-                                                                      updateTypes);
-    MOZ_ASSERT(result != DenseElementResult::Incomplete);
+    DenseElementResult result = obj->setOrExtendDenseElements(cx->asJSContext(), 0, vp, length, updateTypes);
     if (result == DenseElementResult::Failure)
         return nullptr;
-
+    MOZ_ASSERT(result == DenseElementResult::Success);
     return obj;
 }
 
-JSObject*
+ArrayObject*
 js::NewCopiedArrayForCallingAllocationSite(JSContext* cx, const Value* vp, size_t length,
                                            HandleObject proto /* = nullptr */)
 {