From 05c9c752a34ce4c9d246b63e2fbb46eaa946f8b6 Mon Sep 17 00:00:00 2001
From: Gaming4JC <g4jc@hyperbola.info>
Date: Sun, 9 Jun 2019 16:14:01 -0400
Subject: 1336783 - Part 1: Rework on reserved word and remove
 TokenStream::KeywordIsName.

---
 config/check_spidermonkey_style.py                 |   4 +-
 js/src/frontend/GenerateReservedWords.py           | 213 ++++++
 js/src/frontend/Parser.cpp                         | 716 +++++++++------------
 js/src/frontend/Parser.h                           |  48 +-
 js/src/frontend/ReservedWords.h                    |  81 +++
 js/src/frontend/TokenKind.h                        |  99 ++-
 js/src/frontend/TokenStream.cpp                    | 191 +++---
 js/src/frontend/TokenStream.h                      | 135 +---
 .../jit-test/tests/modules/export-declaration.js   |   4 +-
 js/src/js.msg                                      |   1 +
 js/src/jsatom.cpp                                  |  32 -
 js/src/jsatom.h                                    |  35 -
 js/src/moz.build                                   |  10 +-
 js/src/vm/CommonPropertyNames.h                    |  34 +-
 js/src/vm/Keywords.h                               |  66 --
 js/src/wasm/AsmJS.cpp                              |   2 +-
 16 files changed, 900 insertions(+), 771 deletions(-)
 create mode 100644 js/src/frontend/GenerateReservedWords.py
 create mode 100644 js/src/frontend/ReservedWords.h
 delete mode 100644 js/src/vm/Keywords.h

diff --git a/config/check_spidermonkey_style.py b/config/check_spidermonkey_style.py
index 647f403c4..3b5f20037 100644
--- a/config/check_spidermonkey_style.py
+++ b/config/check_spidermonkey_style.py
@@ -63,7 +63,7 @@ included_inclnames_to_ignore = set([
     'devtools/Instruments.h',   # we ignore devtools/ in general
     'double-conversion.h',      # strange MFBT case
     'javascript-trace.h',       # generated in $OBJDIR if HAVE_DTRACE is defined
-    'jsautokw.h',               # generated in $OBJDIR
+    'frontend/ReservedWordsGenerated.h', # generated in $OBJDIR
     'jscustomallocator.h',      # provided by embedders;  allowed to be missing
     'js-config.h',              # generated in $OBJDIR
     'fdlibm.h',                 # fdlibm
@@ -99,7 +99,7 @@ included_inclnames_to_ignore = set([
 # ignore #includes of them when checking #include ordering.
 oddly_ordered_inclnames = set([
     'ctypes/typedefs.h',        # Included multiple times in the body of ctypes/CTypes.h
-    'jsautokw.h',               # Included in the body of frontend/TokenStream.h
+    'frontend/ReservedWordsGenerated.h', # Included in the body of frontend/TokenStream.h
     'jswin.h',                  # Must be #included before <psapi.h>
     'machine/endian.h',         # Must be included after <sys/types.h> on BSD
     'winbase.h',                # Must precede other system headers(?)
diff --git a/js/src/frontend/GenerateReservedWords.py b/js/src/frontend/GenerateReservedWords.py
new file mode 100644
index 000000000..bd698cc5f
--- /dev/null
+++ b/js/src/frontend/GenerateReservedWords.py
@@ -0,0 +1,213 @@
+# 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/.
+
+import re
+import sys
+
+def read_reserved_word_list(filename):
+    macro_pat = re.compile(r"^\s*macro\(([^,]+), *[^,]+, *[^\)]+\)\s*\\?$")
+
+    reserved_word_list = []
+    index = 0
+    with open(filename, 'r') as f:
+        for line in f:
+            m = macro_pat.search(line)
+            if m:
+                reserved_word_list.append((index, m.group(1)))
+                index += 1
+
+    assert(len(reserved_word_list) != 0)
+
+    return reserved_word_list
+
+def line(opt, s):
+    opt['output'].write('{}{}\n'.format('    ' * opt['indent_level'], s))
+
+def indent(opt):
+    opt['indent_level'] += 1
+
+def dedent(opt):
+    opt['indent_level'] -= 1
+
+def span_and_count_at(reserved_word_list, column):
+    assert(len(reserved_word_list) != 0);
+
+    chars_dict = {}
+    for index, word in reserved_word_list:
+        chars_dict[ord(word[column])] = True
+
+    chars = sorted(chars_dict.keys())
+    return chars[-1] - chars[0] + 1, len(chars)
+
+def optimal_switch_column(opt, reserved_word_list, columns, unprocessed_columns):
+    assert(len(reserved_word_list) != 0);
+    assert(unprocessed_columns != 0);
+
+    min_count = 0
+    min_span = 0
+    min_count_index = 0
+    min_span_index = 0
+
+    for index in range(0, unprocessed_columns):
+        span, count = span_and_count_at(reserved_word_list, columns[index])
+        assert(span != 0)
+
+        if span == 1:
+            assert(count == 1)
+            return 1, True
+
+        assert(count != 1)
+        if index == 0 or min_span > span:
+            min_span = span
+            min_span_index = index
+
+        if index == 0 or min_count > count:
+            min_count = count
+            min_count_index = index
+
+    if min_count <= opt['use_if_threshold']:
+        return min_count_index, True
+
+    return min_span_index, False
+
+def split_list_per_column(reserved_word_list, column):
+    assert(len(reserved_word_list) != 0);
+
+    column_dict = {}
+    for item in reserved_word_list:
+        index, word = item
+        per_column = column_dict.setdefault(word[column], [])
+        per_column.append(item)
+
+    return sorted(column_dict.items(), key=lambda (char, word): ord(char))
+
+def generate_letter_switch(opt, unprocessed_columns, reserved_word_list,
+                           columns=None):
+    assert(len(reserved_word_list) != 0);
+
+    if not columns:
+        columns = range(0, unprocessed_columns)
+
+    if len(reserved_word_list) == 1:
+        index, word = reserved_word_list[0]
+
+        if unprocessed_columns == 0:
+            line(opt, 'JSRW_GOT_MATCH({}) /* {} */'.format(index, word))
+            return
+
+        if unprocessed_columns > opt['char_tail_test_threshold']:
+            line(opt, 'JSRW_TEST_GUESS({}) /* {} */'.format(index, word))
+            return
+
+        conds = []
+        for column in columns[0:unprocessed_columns]:
+            quoted = repr(word[column])
+            conds.append('JSRW_AT({})=={}'.format(column, quoted))
+
+        line(opt, 'if ({}) {{'.format(' && '.join(conds)))
+
+        indent(opt)
+        line(opt, 'JSRW_GOT_MATCH({}) /* {} */'.format(index, word))
+        dedent(opt)
+
+        line(opt, '}')
+        line(opt, 'JSRW_NO_MATCH()')
+        return
+
+    assert(unprocessed_columns != 0);
+
+    optimal_column_index, use_if = optimal_switch_column(opt, reserved_word_list,
+                                                         columns,
+                                                         unprocessed_columns)
+    optimal_column = columns[optimal_column_index]
+
+    # Make a copy to avoid breaking passed list.
+    columns = columns[:]
+    columns[optimal_column_index] = columns[unprocessed_columns - 1]
+
+    list_per_column = split_list_per_column(reserved_word_list, optimal_column)
+
+    if not use_if:
+        line(opt, 'switch (JSRW_AT({})) {{'.format(optimal_column))
+
+    for char, reserved_word_list_per_column in list_per_column:
+        quoted = repr(char)
+        if use_if:
+            line(opt, 'if (JSRW_AT({}) == {}) {{'.format(optimal_column,
+                                                         quoted))
+        else:
+            line(opt, '  case {}:'.format(quoted))
+
+        indent(opt)
+        generate_letter_switch(opt, unprocessed_columns - 1,
+                               reserved_word_list_per_column, columns)
+        dedent(opt)
+
+        if use_if:
+            line(opt, '}')
+
+    if not use_if:
+        line(opt, '}')
+
+    line(opt, 'JSRW_NO_MATCH()')
+
+def split_list_per_length(reserved_word_list):
+    assert(len(reserved_word_list) != 0);
+
+    length_dict = {}
+    for item in reserved_word_list:
+        index, word = item
+        per_length = length_dict.setdefault(len(word), [])
+        per_length.append(item)
+
+    return sorted(length_dict.items(), key=lambda (length, word): length)
+
+def generate_switch(opt, reserved_word_list):
+    assert(len(reserved_word_list) != 0);
+
+    line(opt, '/*')
+    line(opt, ' * Generating switch for the list of {} entries:'.format(len(reserved_word_list)))
+    for index, word in reserved_word_list:
+        line(opt, ' * {}'.format(word))
+    line(opt, ' */')
+
+    list_per_length = split_list_per_length(reserved_word_list)
+
+    use_if = False
+    if len(list_per_length) < opt['use_if_threshold']:
+        use_if = True
+
+    if not use_if:
+        line(opt, 'switch (JSRW_LENGTH()) {')
+
+    for length, reserved_word_list_per_length in list_per_length:
+        if use_if:
+            line(opt, 'if (JSRW_LENGTH() == {}) {{'.format(length))
+        else:
+            line(opt, '  case {}:'.format(length))
+
+        indent(opt)
+        generate_letter_switch(opt, length, reserved_word_list_per_length)
+        dedent(opt)
+
+        if use_if:
+            line(opt, '}')
+
+    if not use_if:
+        line(opt, '}')
+    line(opt, 'JSRW_NO_MATCH()')
+
+def main(output, reserved_words_h):
+    reserved_word_list = read_reserved_word_list(reserved_words_h)
+
+    opt = {
+        'indent_level': 1,
+        'use_if_threshold': 3,
+        'char_tail_test_threshold': 4,
+        'output': output
+    }
+    generate_switch(opt, reserved_word_list)
+
+if __name__ == '__main__':
+    main(sys.stdout, *sys.argv[1:])
diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index 923b42870..9b057fb72 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -62,19 +62,27 @@ using AddDeclaredNamePtr = ParseContext::Scope::AddDeclaredNamePtr;
 using BindingIter = ParseContext::Scope::BindingIter;
 using UsedNamePtr = UsedNameTracker::UsedNameMap::Ptr;
 
-/* Read a token. Report an error and return null() if that token isn't of type tt. */
-#define MUST_MATCH_TOKEN_MOD(tt, modifier, errorNumber)                                     \
+// Read a token. Report an error and return null() if that token doesn't match
+// to the given func's condition.
+#define MUST_MATCH_TOKEN_FUNC_MOD(func, modifier, errorNumber)                              \
     JS_BEGIN_MACRO                                                                          \
         TokenKind token;                                                                    \
         if (!tokenStream.getToken(&token, modifier))                                        \
             return null();                                                                  \
-        if (token != tt) {                                                                  \
+        if (!(func)(token)) {                                                               \
             error(errorNumber);                                                             \
             return null();                                                                  \
         }                                                                                   \
     JS_END_MACRO
 
-#define MUST_MATCH_TOKEN(tt, errno) MUST_MATCH_TOKEN_MOD(tt, TokenStream::None, errno)
+#define MUST_MATCH_TOKEN_MOD(tt, modifier, errorNumber) \
+    MUST_MATCH_TOKEN_FUNC_MOD([](TokenKind tok) { return tok == tt; }, modifier, errorNumber)
+
+#define MUST_MATCH_TOKEN(tt, errorNumber) \
+    MUST_MATCH_TOKEN_MOD(tt, TokenStream::None, errorNumber)
+
+#define MUST_MATCH_TOKEN_FUNC(func, errorNumber) \
+    MUST_MATCH_TOKEN_FUNC_MOD(func, TokenStream::None, errorNumber)
 
 template <class T, class U>
 static inline void
@@ -753,7 +761,8 @@ ParserBase::ParserBase(ExclusiveContext* cx, LifoAlloc& alloc,
     checkOptionsCalled(false),
 #endif
     abortedSyntaxParse(false),
-    isUnexpectedEOF_(false)
+    isUnexpectedEOF_(false),
+    awaitIsKeyword_(false)
 {
     cx->perThreadData->frontendCollectionPool.addActiveCompilation();
     tempPoolMark = alloc.mark();
@@ -810,6 +819,22 @@ Parser<ParseHandler>::~Parser()
     MOZ_ASSERT(checkOptionsCalled);
 }
 
+template <>
+void
+Parser<SyntaxParseHandler>::setAwaitIsKeyword(bool isKeyword)
+{
+    awaitIsKeyword_ = isKeyword;
+}
+
+template <>
+void
+Parser<FullParseHandler>::setAwaitIsKeyword(bool isKeyword)
+{
+    awaitIsKeyword_ = isKeyword;
+    if (Parser<SyntaxParseHandler>* parser = handler.syntaxParser)
+        parser->setAwaitIsKeyword(isKeyword);
+}
+
 template <typename ParseHandler>
 ObjectBox*
 Parser<ParseHandler>::newObjectBox(JSObject* obj)
@@ -936,7 +961,7 @@ Parser<ParseHandler>::parse()
 
 /*
  * Strict mode forbids introducing new definitions for 'eval', 'arguments', or
- * for any strict mode reserved keyword.
+ * for any strict mode reserved word.
  */
 bool
 ParserBase::isValidStrictBinding(PropertyName* name)
@@ -945,7 +970,8 @@ ParserBase::isValidStrictBinding(PropertyName* name)
            name != context->names().arguments &&
            name != context->names().let &&
            name != context->names().static_ &&
-           !(IsKeyword(name) && name != context->names().await);
+           name != context->names().yield &&
+           !IsStrictReservedWord(name);
 }
 
 /*
@@ -959,13 +985,30 @@ Parser<ParseHandler>::checkStrictBinding(PropertyName* name, TokenPos pos)
     if (!pc->sc()->needStrictChecks())
         return true;
 
-    if (!isValidStrictBinding(name)) {
-        JSAutoByteString bytes;
-        if (!AtomToPrintableString(context, name, &bytes))
-            return false;
-        return strictModeErrorAt(pos.begin, JSMSG_BAD_BINDING, bytes.ptr());
+    if (name == context->names().arguments)
+        return strictModeErrorAt(pos.begin, JSMSG_BAD_BINDING, "arguments");
+
+    if (name == context->names().eval)
+        return strictModeErrorAt(pos.begin, JSMSG_BAD_BINDING, "eval");
+
+    if (name == context->names().let) {
+        errorAt(pos.begin, JSMSG_RESERVED_ID, "let");
+        return false;
     }
 
+    if (name == context->names().static_) {
+        errorAt(pos.begin, JSMSG_RESERVED_ID, "static");
+        return false;
+    }
+
+    if (name == context->names().yield) {
+        errorAt(pos.begin, JSMSG_RESERVED_ID, "yield");
+        return false;
+    }
+
+    if (IsStrictReservedWord(name))
+        return strictModeErrorAt(pos.begin, JSMSG_RESERVED_ID, ReservedWordToCharZ(name));
+
     return true;
 }
 
@@ -2094,7 +2137,7 @@ Parser<FullParseHandler>::moduleBody(ModuleSharedContext* modulesc)
     if (!mn)
         return null();
 
-    AutoAwaitIsKeyword awaitIsKeyword(&tokenStream, true);
+    AutoAwaitIsKeyword<FullParseHandler> awaitIsKeyword(this, true);
     ParseNode* pn = statementList(YieldIsKeyword);
     if (!pn)
         return null();
@@ -2417,7 +2460,7 @@ Parser<FullParseHandler>::standaloneFunction(HandleFunction fun,
     funpc.setIsStandaloneFunctionBody();
 
     YieldHandling yieldHandling = GetYieldHandling(generatorKind, asyncKind);
-    AutoAwaitIsKeyword awaitIsKeyword(&tokenStream, asyncKind == AsyncFunction);
+    AutoAwaitIsKeyword<FullParseHandler> awaitIsKeyword(this, asyncKind == AsyncFunction);
     if (!functionFormalParametersAndBody(InAllowed, yieldHandling, fn, Statement,
                                          parameterListEnd, /* isStandaloneFunction = */ true))
     {
@@ -2719,10 +2762,7 @@ Parser<ParseHandler>::matchOrInsertSemicolonHelper(TokenStream::Modifier modifie
          * Detect this situation and throw an understandable error.  Otherwise
          * we'd throw a confusing "missing ; before statement" error.
          */
-        if (!pc->isAsync() &&
-            tokenStream.currentToken().type == TOK_NAME &&
-            tokenStream.currentName() == context->names().await)
-        {
+        if (!pc->isAsync() && tokenStream.currentToken().type == TOK_AWAIT) {
             error(JSMSG_AWAIT_OUTSIDE_ASYNC);
             return false;
         }
@@ -2845,7 +2885,7 @@ Parser<ParseHandler>::functionArguments(YieldHandling yieldHandling, FunctionSyn
         firstTokenModifier = funbox->isAsync() ? TokenStream::None : TokenStream::Operand;
         if (!tokenStream.peekToken(&tt, firstTokenModifier))
             return false;
-        if (tt == TOK_NAME || tt == TOK_YIELD) {
+        if (TokenKindIsPossibleIdentifier(tt)) {
             parenFreeArrow = true;
             argModifier = firstTokenModifier;
         }
@@ -2901,7 +2941,7 @@ Parser<ParseHandler>::functionArguments(YieldHandling yieldHandling, FunctionSyn
             if (!tokenStream.getToken(&tt, argModifier))
                 return false;
             argModifier = TokenStream::Operand;
-            MOZ_ASSERT_IF(parenFreeArrow, tt == TOK_NAME || tt == TOK_YIELD);
+            MOZ_ASSERT_IF(parenFreeArrow, TokenKindIsPossibleIdentifier(tt));
 
             if (tt == TOK_TRIPLEDOT) {
                 if (IsSetterKind(kind)) {
@@ -2922,7 +2962,7 @@ Parser<ParseHandler>::functionArguments(YieldHandling yieldHandling, FunctionSyn
                 if (!tokenStream.getToken(&tt))
                     return false;
 
-                if (tt != TOK_NAME && tt != TOK_YIELD && tt != TOK_LB && tt != TOK_LC) {
+                if (!TokenKindIsPossibleIdentifier(tt) && tt != TOK_LB && tt != TOK_LC) {
                     error(JSMSG_NO_REST_NAME);
                     return false;
                 }
@@ -2952,20 +2992,15 @@ Parser<ParseHandler>::functionArguments(YieldHandling yieldHandling, FunctionSyn
                 break;
               }
 
-              case TOK_NAME:
-              case TOK_YIELD: {
-                if (parenFreeArrow)
-                    funbox->setStart(tokenStream);
-
-                if (funbox->isAsync() && tokenStream.currentName() == context->names().await) {
-                    // `await` is already gotten as TOK_NAME for the following
-                    // case:
-                    //
-                    //   async await => 1
-                    error(JSMSG_RESERVED_ID, "await");
+              default: {
+                if (!TokenKindIsPossibleIdentifier(tt)) {
+                    error(JSMSG_MISSING_FORMAL);
                     return false;
                 }
 
+                if (parenFreeArrow)
+                    funbox->setStart(tokenStream);
+
                 RootedPropertyName name(context, bindingIdentifier(yieldHandling));
                 if (!name)
                     return false;
@@ -2980,10 +3015,6 @@ Parser<ParseHandler>::functionArguments(YieldHandling yieldHandling, FunctionSyn
 
                 break;
               }
-
-              default:
-                error(JSMSG_MISSING_FORMAL);
-                return false;
             }
 
             if (positionalFormals.length() >= ARGNO_LIMIT) {
@@ -3507,7 +3538,7 @@ Parser<ParseHandler>::functionFormalParametersAndBody(InHandling inHandling,
     FunctionBox* funbox = pc->functionBox();
     RootedFunction fun(context, funbox->function());
 
-    AutoAwaitIsKeyword awaitIsKeyword(&tokenStream, funbox->isAsync());
+    AutoAwaitIsKeyword<ParseHandler> awaitIsKeyword(this, funbox->isAsync());
     if (!functionArguments(yieldHandling, kind, pn))
         return false;
 
@@ -3656,7 +3687,7 @@ Parser<ParseHandler>::functionStmt(uint32_t preludeStart, YieldHandling yieldHan
     }
 
     RootedPropertyName name(context);
-    if (tt == TOK_NAME || tt == TOK_YIELD) {
+    if (TokenKindIsPossibleIdentifier(tt)) {
         name = bindingIdentifier(yieldHandling);
         if (!name)
             return null();
@@ -3712,7 +3743,7 @@ Parser<ParseHandler>::functionExpr(uint32_t preludeStart, InvokedPrediction invo
 {
     MOZ_ASSERT(tokenStream.isCurrentTokenType(TOK_FUNCTION));
 
-    AutoAwaitIsKeyword awaitIsKeyword(&tokenStream, asyncKind == AsyncFunction);
+    AutoAwaitIsKeyword<ParseHandler> awaitIsKeyword(this, asyncKind == AsyncFunction);
     GeneratorKind generatorKind = asyncKind == AsyncFunction ? StarGenerator : NotGenerator;
     TokenKind tt;
     if (!tokenStream.getToken(&tt))
@@ -3731,7 +3762,7 @@ Parser<ParseHandler>::functionExpr(uint32_t preludeStart, InvokedPrediction invo
     YieldHandling yieldHandling = GetYieldHandling(generatorKind, asyncKind);
 
     RootedPropertyName name(context);
-    if (tt == TOK_NAME || tt == TOK_YIELD) {
+    if (TokenKindIsPossibleIdentifier(tt)) {
         name = bindingIdentifier(yieldHandling);
         if (!name)
             return null();
@@ -3768,18 +3799,6 @@ IsEscapeFreeStringLiteral(const TokenPos& pos, JSAtom* str)
     return pos.begin + str->length() + 2 == pos.end;
 }
 
-template <typename ParseHandler>
-bool
-Parser<ParseHandler>::checkUnescapedName()
-{
-    const Token& token = tokenStream.currentToken();
-    if (!token.nameContainsEscape())
-        return true;
-
-    errorAt(token.pos.begin, JSMSG_ESCAPED_KEYWORD);
-    return false;
-}
-
 template <>
 bool
 Parser<SyntaxParseHandler>::asmJS(Node list)
@@ -3998,7 +4017,7 @@ Parser<ParseHandler>::matchLabel(YieldHandling yieldHandling, MutableHandle<Prop
     if (!tokenStream.peekTokenSameLine(&tt, TokenStream::Operand))
         return false;
 
-    if (tt == TOK_NAME || tt == TOK_YIELD) {
+    if (TokenKindIsPossibleIdentifier(tt)) {
         tokenStream.consumeKnownToken(tt, TokenStream::Operand);
 
         label.set(labelIdentifier(yieldHandling));
@@ -4551,7 +4570,8 @@ Parser<ParseHandler>::declarationName(Node decl, DeclarationKind declKind, Token
                                       ParseNodeKind* forHeadKind, Node* forInOrOfExpression)
 {
     // Anything other than TOK_YIELD or TOK_NAME is an error.
-    if (tt != TOK_NAME && tt != TOK_YIELD) {
+    // Anything other than possible identifier is an error.
+    if (!TokenKindIsPossibleIdentifier(tt)) {
         error(JSMSG_NO_VARIABLE_NAME);
         return null();
     }
@@ -4721,16 +4741,13 @@ Parser<FullParseHandler>::namedImportsOrNamespaceImport(TokenKind tt, Node impor
             // Handle the forms |import {} from 'a'| and
             // |import { ..., } from 'a'| (where ... is non empty), by
             // escaping the loop early if the next token is }.
-            if (!tokenStream.getToken(&tt, TokenStream::KeywordIsName))
+            if (!tokenStream.getToken(&tt))
                 return false;
 
             if (tt == TOK_RC)
                 break;
 
-            // If the next token is a keyword, the previous call to
-            // peekToken matched it as a TOK_NAME, and put it in the
-            // lookahead buffer, so this call will match keywords as well.
-            if (tt != TOK_NAME) {
+            if (!TokenKindIsPossibleIdentifierName(tt)) {
                 error(JSMSG_NO_IMPORT_NAME);
                 return false;
             }
@@ -4738,23 +4755,16 @@ Parser<FullParseHandler>::namedImportsOrNamespaceImport(TokenKind tt, Node impor
             Rooted<PropertyName*> importName(context, tokenStream.currentName());
             TokenPos importNamePos = pos();
 
-            TokenKind maybeAs;
-            if (!tokenStream.peekToken(&maybeAs))
+            bool matched;
+            if (!tokenStream.matchToken(&matched, TOK_AS))
                 return null();
 
-            if (maybeAs == TOK_NAME &&
-                tokenStream.nextName() == context->names().as)
-            {
-                tokenStream.consumeKnownToken(TOK_NAME);
-
-                if (!checkUnescapedName())
-                    return false;
-
+            if (matched) {
                 TokenKind afterAs;
                 if (!tokenStream.getToken(&afterAs))
                     return false;
 
-                if (afterAs != TOK_NAME && afterAs != TOK_YIELD) {
+                if (!TokenKindIsPossibleIdentifierName(afterAs)) {
                     error(JSMSG_NO_BINDING_NAME);
                     return false;
                 }
@@ -4764,10 +4774,7 @@ Parser<FullParseHandler>::namedImportsOrNamespaceImport(TokenKind tt, Node impor
                 // by the keyword 'as'.
                 // See the ImportSpecifier production in ES6 section 15.2.2.
                 if (IsKeyword(importName)) {
-                    JSAutoByteString bytes;
-                    if (!AtomToPrintableString(context, importName, &bytes))
-                        return false;
-                    error(JSMSG_AS_AFTER_RESERVED_WORD, bytes.ptr());
+                    error(JSMSG_AS_AFTER_RESERVED_WORD, ReservedWordToCharZ(importName));
                     return false;
                 }
             }
@@ -4806,18 +4813,10 @@ Parser<FullParseHandler>::namedImportsOrNamespaceImport(TokenKind tt, Node impor
         }
     } else {
         MOZ_ASSERT(tt == TOK_MUL);
-        if (!tokenStream.getToken(&tt))
-            return false;
 
-        if (tt != TOK_NAME || tokenStream.currentName() != context->names().as) {
-            error(JSMSG_AS_AFTER_IMPORT_STAR);
-            return false;
-        }
+        MUST_MATCH_TOKEN(TOK_AS, JSMSG_AS_AFTER_IMPORT_STAR);
 
-        if (!checkUnescapedName())
-            return false;
-
-        MUST_MATCH_TOKEN(TOK_NAME, JSMSG_NO_BINDING_NAME);
+        MUST_MATCH_TOKEN_FUNC(TokenKindIsPossibleIdentifierName, JSMSG_NO_BINDING_NAME);
 
         Node importName = newName(context->names().star);
         if (!importName)
@@ -4878,8 +4877,15 @@ Parser<FullParseHandler>::importDeclaration()
     if (!importSpecSet)
         return null();
 
-    if (tt == TOK_NAME || tt == TOK_LC || tt == TOK_MUL) {
-        if (tt == TOK_NAME) {
+    if (tt == TOK_STRING) {
+        // Handle the form |import 'a'| by leaving the list empty. This is
+        // equivalent to |import {} from 'a'|.
+        importSpecSet->pn_pos.end = importSpecSet->pn_pos.begin;
+    } else {
+        if (tt == TOK_LC || tt == TOK_MUL) {
+            if (!namedImportsOrNamespaceImport(tt, importSpecSet))
+                return null();
+        } else if (TokenKindIsPossibleIdentifierName(tt)) {
             // Handle the form |import a from 'b'|, by adding a single import
             // specifier to the list, with 'default' as the import name and
             // 'a' as the binding name. This is equivalent to
@@ -4922,29 +4928,19 @@ Parser<FullParseHandler>::importDeclaration()
                     return null();
             }
         } else {
-            if (!namedImportsOrNamespaceImport(tt, importSpecSet))
-                return null();
+            error(JSMSG_DECLARATION_AFTER_IMPORT);
+            return null();
         }
 
         if (!tokenStream.getToken(&tt))
             return null();
 
-        if (tt != TOK_NAME || tokenStream.currentName() != context->names().from) {
+        if (tt != TOK_FROM) {
             error(JSMSG_FROM_AFTER_IMPORT_CLAUSE);
             return null();
         }
 
-        if (!checkUnescapedName())
-            return null();
-
         MUST_MATCH_TOKEN(TOK_STRING, JSMSG_MODULE_SPEC_AFTER_FROM);
-    } else if (tt == TOK_STRING) {
-        // Handle the form |import 'a'| by leaving the list empty. This is
-        // equivalent to |import {} from 'a'|.
-        importSpecSet->pn_pos.end = importSpecSet->pn_pos.begin;
-    } else {
-        error(JSMSG_DECLARATION_AFTER_IMPORT);
-        return null();
     }
 
     Node moduleSpec = stringLiteral();
@@ -5050,7 +5046,7 @@ Parser<FullParseHandler>::exportDeclaration()
             if (tt == TOK_RC)
                 break;
 
-            if (tt != TOK_NAME) {
+            if (!TokenKindIsPossibleIdentifierName(tt)) {
                 error(JSMSG_NO_BINDING_NAME);
                 return null();
             }
@@ -5060,10 +5056,10 @@ Parser<FullParseHandler>::exportDeclaration()
                 return null();
 
             bool foundAs;
-            if (!tokenStream.matchContextualKeyword(&foundAs, context->names().as))
+            if (!tokenStream.matchToken(&foundAs, TOK_AS))
                 return null();
             if (foundAs)
-                MUST_MATCH_TOKEN_MOD(TOK_NAME, TokenStream::KeywordIsName, JSMSG_NO_EXPORT_NAME);
+                MUST_MATCH_TOKEN_FUNC(TokenKindIsPossibleIdentifierName, JSMSG_NO_EXPORT_NAME);
 
             Node exportName = newName(tokenStream.currentName());
             if (!exportName)
@@ -5098,21 +5094,18 @@ Parser<FullParseHandler>::exportDeclaration()
         //   from "foo"; // a single ExportDeclaration
         //
         // But if it doesn't, we might have an ASI opportunity in Operand
-        // context, so simply matching a contextual keyword won't work:
+        // context:
         //
         //   export { x }   // ExportDeclaration, terminated by ASI
         //   fro\u006D      // ExpressionStatement, the name "from"
         //
         // In that case let matchOrInsertSemicolonAfterNonExpression sort out
         // ASI or any necessary error.
-        TokenKind tt;
-        if (!tokenStream.getToken(&tt, TokenStream::Operand))
+        bool matched;
+        if (!tokenStream.matchToken(&matched, TOK_FROM, TokenStream::Operand))
             return null();
 
-        if (tt == TOK_NAME &&
-            tokenStream.currentToken().name() == context->names().from &&
-            !tokenStream.currentToken().nameContainsEscape())
-        {
+        if (matched) {
             MUST_MATCH_TOKEN(TOK_STRING, JSMSG_MODULE_SPEC_AFTER_FROM);
 
             Node moduleSpec = stringLiteral();
@@ -5129,8 +5122,6 @@ Parser<FullParseHandler>::exportDeclaration()
             return node;
         }
 
-        tokenStream.ungetToken();
-
         if (!matchOrInsertSemicolonAfterNonExpression())
             return null();
         break;
@@ -5151,14 +5142,11 @@ Parser<FullParseHandler>::exportDeclaration()
 
         if (!tokenStream.getToken(&tt))
             return null();
-        if (tt != TOK_NAME || tokenStream.currentName() != context->names().from) {
+        if (tt != TOK_FROM) {
             error(JSMSG_FROM_AFTER_EXPORT_STAR);
             return null();
         }
 
-        if (!checkUnescapedName())
-            return null();
-
         MUST_MATCH_TOKEN(TOK_STRING, JSMSG_MODULE_SPEC_AFTER_FROM);
 
         Node moduleSpec = stringLiteral();
@@ -5227,10 +5215,7 @@ Parser<FullParseHandler>::exportDeclaration()
                 return null();
             break;
           default: {
-            if (tt == TOK_NAME &&
-                tokenStream.currentName() == context->names().async &&
-                !tokenStream.currentToken().nameContainsEscape())
-            {
+            if (tt == TOK_ASYNC) {
                 TokenKind nextSameLine = TOK_EOF;
                 if (!tokenStream.peekTokenSameLine(&nextSameLine))
                     return null();
@@ -5276,19 +5261,13 @@ Parser<FullParseHandler>::exportDeclaration()
             return null();
         break;
 
-      case TOK_NAME:
-        if (tokenStream.currentName() == context->names().let) {
-            if (!checkUnescapedName())
-                return null();
-
-            kid = lexicalDeclaration(YieldIsName, /* isConst = */ false);
-            if (!kid)
-                return null();
-            if (!checkExportedNamesForDeclaration(kid))
-                return null();
-            break;
-        }
-        MOZ_FALLTHROUGH;
+      case TOK_LET:
+        kid = lexicalDeclaration(YieldIsName, /* isConst = */ false);
+        if (!kid)
+            return null();
+        if (!checkExportedNamesForDeclaration(kid))
+            return null();
+        break;
 
       default:
         error(JSMSG_DECLARATION_AFTER_EXPORT);
@@ -5338,10 +5317,7 @@ Parser<ParseHandler>::consequentOrAlternative(YieldHandling yieldHandling)
     //
     // Careful!  FunctionDeclaration doesn't include generators or async
     // functions.
-    if (next == TOK_NAME &&
-        !tokenStream.nextNameContainsEscape() &&
-        tokenStream.nextName() == context->names().async)
-    {
+    if (next == TOK_ASYNC) {
         tokenStream.consumeKnownToken(next, TokenStream::Operand);
 
         // Peek only on the same line: ExpressionStatement's lookahead
@@ -5514,13 +5490,9 @@ Parser<ParseHandler>::matchInOrOf(bool* isForInp, bool* isForOfp)
         return false;
 
     *isForInp = tt == TOK_IN;
-    *isForOfp = tt == TOK_NAME && tokenStream.currentToken().name() == context->names().of;
-    if (!*isForInp && !*isForOfp) {
+    *isForOfp = tt == TOK_OF;
+    if (!*isForInp && !*isForOfp)
         tokenStream.ungetToken();
-    } else {
-        if (tt == TOK_NAME && !checkUnescapedName())
-            return false;
-    }
 
     MOZ_ASSERT_IF(*isForInp || *isForOfp, *isForInp != *isForOfp);
     return true;
@@ -5570,15 +5542,12 @@ Parser<ParseHandler>::forHeadStart(YieldHandling yieldHandling,
     if (tt == TOK_CONST) {
         parsingLexicalDeclaration = true;
         tokenStream.consumeKnownToken(tt, TokenStream::Operand);
-    } else if (tt == TOK_NAME &&
-               tokenStream.nextName() == context->names().let &&
-               !tokenStream.nextNameContainsEscape())
-    {
+    } else if (tt == TOK_LET) {
         // We could have a {For,Lexical}Declaration, or we could have a
         // LeftHandSideExpression with lookahead restrictions so it's not
         // ambiguous with the former.  Check for a continuation of the former
         // to decide which we have.
-        tokenStream.consumeKnownToken(TOK_NAME, TokenStream::Operand);
+        tokenStream.consumeKnownToken(TOK_LET, TokenStream::Operand);
 
         TokenKind next;
         if (!tokenStream.peekToken(&next))
@@ -5699,7 +5668,7 @@ Parser<ParseHandler>::forStatement(YieldHandling yieldHandling)
 
     if (allowsForEachIn()) {
         bool matched;
-        if (!tokenStream.matchContextualKeyword(&matched, context->names().each))
+        if (!tokenStream.matchToken(&matched, TOK_EACH))
             return null();
         if (matched) {
             iflags = JSITER_FOREACH;
@@ -6410,12 +6379,12 @@ Parser<ParseHandler>::tryStatement(YieldHandling yieldHandling)
      * kid3 is the finally statement
      *
      * catch nodes are ternary.
-     * kid1 is the lvalue (TOK_NAME, TOK_LB, or TOK_LC)
+     * kid1 is the lvalue (possible identifier, TOK_LB, or TOK_LC)
      * kid2 is the catch guard or null if no guard
      * kid3 is the catch block
      *
      * catch lvalue nodes are either:
-     *   TOK_NAME for a single identifier
+     *   a single identifier
      *   TOK_RB or TOK_RC for a destructuring left-hand side
      *
      * finally nodes are TOK_LC statement lists.
@@ -6490,8 +6459,12 @@ Parser<ParseHandler>::tryStatement(YieldHandling yieldHandling)
                     return null();
                 break;
 
-              case TOK_NAME:
-              case TOK_YIELD: {
+              default: {
+                if (!TokenKindIsPossibleIdentifierName(tt)) {
+                    error(JSMSG_CATCH_IDENTIFIER);
+                    return null();
+                }
+
                 RootedPropertyName param(context, bindingIdentifier(yieldHandling));
                 if (!param)
                     return null();
@@ -6502,10 +6475,6 @@ Parser<ParseHandler>::tryStatement(YieldHandling yieldHandling)
                     return null();
                 break;
               }
-
-              default:
-                error(JSMSG_CATCH_IDENTIFIER);
-                return null();
             }
 
             Node catchGuard = null();
@@ -6664,7 +6633,7 @@ Parser<ParseHandler>::classDefinition(YieldHandling yieldHandling,
         return null();
 
     RootedPropertyName name(context);
-    if (tt == TOK_NAME || tt == TOK_YIELD) {
+    if (TokenKindIsPossibleIdentifier(tt)) {
         name = bindingIdentifier(yieldHandling);
         if (!name)
             return null();
@@ -6721,7 +6690,7 @@ Parser<ParseHandler>::classDefinition(YieldHandling yieldHandling,
     bool seenConstructor = false;
     for (;;) {
         TokenKind tt;
-        if (!tokenStream.getToken(&tt, TokenStream::KeywordIsName))
+        if (!tokenStream.getToken(&tt))
             return null();
         if (tt == TOK_RC)
             break;
@@ -6730,22 +6699,18 @@ Parser<ParseHandler>::classDefinition(YieldHandling yieldHandling,
             continue;
 
         bool isStatic = false;
-        if (tt == TOK_NAME && tokenStream.currentName() == context->names().static_) {
-            if (!tokenStream.peekToken(&tt, TokenStream::KeywordIsName))
+        if (tt == TOK_STATIC) {
+            if (!tokenStream.peekToken(&tt))
                 return null();
             if (tt == TOK_RC) {
-                tokenStream.consumeKnownToken(tt, TokenStream::KeywordIsName);
+                tokenStream.consumeKnownToken(tt);
                 error(JSMSG_UNEXPECTED_TOKEN, "property name", TokenKindToDesc(tt));
                 return null();
             }
 
             if (tt != TOK_LP) {
-                if (!checkUnescapedName())
-                    return null();
-
                 isStatic = true;
             } else {
-                tokenStream.addModifierException(TokenStream::NoneIsKeywordIsName);
                 tokenStream.ungetToken();
             }
         } else {
@@ -6865,9 +6830,7 @@ template <class ParseHandler>
 bool
 Parser<ParseHandler>::nextTokenContinuesLetDeclaration(TokenKind next, YieldHandling yieldHandling)
 {
-    MOZ_ASSERT(tokenStream.isCurrentTokenType(TOK_NAME));
-    MOZ_ASSERT(tokenStream.currentName() == context->names().let);
-    MOZ_ASSERT(!tokenStream.currentToken().nameContainsEscape());
+    MOZ_ASSERT(tokenStream.isCurrentTokenType(TOK_LET));
 
 #ifdef DEBUG
     TokenKind verify;
@@ -6879,18 +6842,19 @@ Parser<ParseHandler>::nextTokenContinuesLetDeclaration(TokenKind next, YieldHand
     if (next == TOK_LB || next == TOK_LC)
         return true;
 
-    // Otherwise a let declaration must have a name.
-    if (next == TOK_NAME) {
-        if (tokenStream.nextName() == context->names().yield) {
-            MOZ_ASSERT(tokenStream.nextNameContainsEscape(),
-                       "token stream should interpret unescaped 'yield' as TOK_YIELD");
-
-            // Same as |next == TOK_YIELD|.
-            return yieldHandling == YieldIsName;
-        }
+    // If we have the name "yield", the grammar parameter exactly states
+    // whether this is okay.  (This wasn't true for SpiderMonkey's ancient
+    // legacy generator syntax, but that's dead now.)  If YieldIsName,
+    // declaration-parsing code will (if necessary) enforce a strict mode
+    // restriction on defining "yield".  If YieldIsKeyword, consider this the
+    // end of the declaration, in case ASI induces a semicolon that makes the
+    // "yield" valid.
+    if (next == TOK_YIELD)
+        return yieldHandling == YieldIsName;
 
-        // One non-"yield" TOK_NAME edge case deserves special comment.
-        // Consider this:
+    // Otherwise a let declaration must have a name.
+    if (TokenKindIsPossibleIdentifier(next)) {
+        // A "let" edge case deserves special comment.  Consider this:
         //
         //   let     // not an ASI opportunity
         //   let;
@@ -6903,16 +6867,6 @@ Parser<ParseHandler>::nextTokenContinuesLetDeclaration(TokenKind next, YieldHand
         return true;
     }
 
-    // If we have the name "yield", the grammar parameter exactly states
-    // whether this is okay.  (This wasn't true for SpiderMonkey's ancient
-    // legacy generator syntax, but that's dead now.)  If YieldIsName,
-    // declaration-parsing code will (if necessary) enforce a strict mode
-    // restriction on defining "yield".  If YieldIsKeyword, consider this the
-    // end of the declaration, in case ASI induces a semicolon that makes the
-    // "yield" valid.
-    if (next == TOK_YIELD)
-        return yieldHandling == YieldIsName;
-
     // Otherwise not a let declaration.
     return false;
 }
@@ -6975,16 +6929,21 @@ Parser<ParseHandler>::statement(YieldHandling yieldHandling)
         return expressionStatement(yieldHandling);
       }
 
-      case TOK_NAME: {
+      default: {
+        // Avoid getting next token with None.
+        if (tt == TOK_AWAIT && pc->isAsync())
+            return expressionStatement(yieldHandling);
+
+        if (!TokenKindIsPossibleIdentifier(tt))
+            return expressionStatement(yieldHandling);
+
         TokenKind next;
         if (!tokenStream.peekToken(&next))
             return null();
 
         // |let| here can only be an Identifier, not a declaration.  Give nicer
         // errors for declaration-looking typos.
-        if (!tokenStream.currentToken().nameContainsEscape() &&
-            tokenStream.currentName() == context->names().let)
-        {
+        if (tt == TOK_LET) {
             bool forbiddenLetDeclaration = false;
 
             if (pc->sc()->strict() || versionNumber() >= JSVERSION_1_7) {
@@ -6994,7 +6953,7 @@ Parser<ParseHandler>::statement(YieldHandling yieldHandling)
             } else if (next == TOK_LB) {
                 // Enforce ExpressionStatement's 'let [' lookahead restriction.
                 forbiddenLetDeclaration = true;
-            } else if (next == TOK_LC || next == TOK_NAME) {
+            } else if (next == TOK_LC || TokenKindIsPossibleIdentifier(next)) {
                 // 'let {' and 'let foo' aren't completely forbidden, if ASI
                 // causes 'let' to be the entire Statement.  But if they're
                 // same-line, we can aggressively give a better error message.
@@ -7005,7 +6964,7 @@ Parser<ParseHandler>::statement(YieldHandling yieldHandling)
                 if (!tokenStream.peekTokenSameLine(&nextSameLine))
                     return null();
 
-                MOZ_ASSERT(nextSameLine == TOK_NAME ||
+                MOZ_ASSERT(TokenKindIsPossibleIdentifier(nextSameLine) ||
                            nextSameLine == TOK_LC ||
                            nextSameLine == TOK_EOL);
 
@@ -7029,9 +6988,6 @@ Parser<ParseHandler>::statement(YieldHandling yieldHandling)
       case TOK_NEW:
         return expressionStatement(yieldHandling, PredictInvoked);
 
-      default:
-        return expressionStatement(yieldHandling);
-
       // IfStatement[?Yield, ?Return]
       case TOK_IF:
         return ifStatement(yieldHandling);
@@ -7077,7 +7033,7 @@ Parser<ParseHandler>::statement(YieldHandling yieldHandling)
         return withStatement(yieldHandling);
 
       // LabelledStatement[?Yield, ?Return]
-      // This is really handled by TOK_NAME and TOK_YIELD cases above.
+      // This is really handled by default and TOK_YIELD cases above.
 
       // ThrowStatement[?Yield]
       case TOK_THROW:
@@ -7183,28 +7139,29 @@ Parser<ParseHandler>::statementListItem(YieldHandling yieldHandling,
         return expressionStatement(yieldHandling);
       }
 
-      case TOK_NAME: {
+      default: {
+        // Avoid getting next token with None.
+        if (tt == TOK_AWAIT && pc->isAsync())
+            return expressionStatement(yieldHandling);
+
+        if (!TokenKindIsPossibleIdentifier(tt))
+            return expressionStatement(yieldHandling);
+
         TokenKind next;
         if (!tokenStream.peekToken(&next))
             return null();
 
-        if (!tokenStream.currentToken().nameContainsEscape()) {
-            if (tokenStream.currentName() == context->names().let &&
-                nextTokenContinuesLetDeclaration(next, yieldHandling))
-            {
-                return lexicalDeclaration(yieldHandling, /* isConst = */ false);
-            }
+        if (tt == TOK_LET && nextTokenContinuesLetDeclaration(next, yieldHandling))
+            return lexicalDeclaration(yieldHandling, /* isConst = */ false);
 
-            if (tokenStream.currentName() == context->names().async) {
-                TokenKind nextSameLine = TOK_EOF;
-                if (!tokenStream.peekTokenSameLine(&nextSameLine)) {
-                    return null();
-                }
-                if (nextSameLine == TOK_FUNCTION) {
-                    uint32_t preludeStart = pos().begin;
-                    tokenStream.consumeKnownToken(TOK_FUNCTION);
-                    return functionStmt(preludeStart, yieldHandling, NameRequired, AsyncFunction);
-                }
+        if (tt == TOK_ASYNC) {
+            TokenKind nextSameLine = TOK_EOF;
+            if (!tokenStream.peekTokenSameLine(&nextSameLine))
+                return null();
+            if (nextSameLine == TOK_FUNCTION) {
+                uint32_t preludeStart = pos().begin;
+                tokenStream.consumeKnownToken(TOK_FUNCTION);
+                return functionStmt(preludeStart, yieldHandling, NameRequired, AsyncFunction);
             }
         }
 
@@ -7217,9 +7174,6 @@ Parser<ParseHandler>::statementListItem(YieldHandling yieldHandling,
       case TOK_NEW:
         return expressionStatement(yieldHandling, PredictInvoked);
 
-      default:
-        return expressionStatement(yieldHandling);
-
       // IfStatement[?Yield, ?Return]
       case TOK_IF:
         return ifStatement(yieldHandling);
@@ -7265,7 +7219,7 @@ Parser<ParseHandler>::statementListItem(YieldHandling yieldHandling,
         return withStatement(yieldHandling);
 
       // LabelledStatement[?Yield, ?Return]
-      // This is really handled by TOK_NAME and TOK_YIELD cases above.
+      // This is really handled by default and TOK_YIELD cases above.
 
       // ThrowStatement[?Yield]
       case TOK_THROW:
@@ -7631,6 +7585,9 @@ Parser<ParseHandler>::assignExpr(InHandling inHandling, YieldHandling yieldHandl
 
     bool endsExpr;
 
+    // This only handles identifiers that *never* have special meaning anywhere
+    // in the language.  Contextual keywords, reserved words in strict mode,
+    // and other hard cases are handled outside this fast path.
     if (tt == TOK_NAME) {
         if (!tokenStream.nextTokenEndsExpr(&endsExpr))
             return null();
@@ -7661,15 +7618,12 @@ Parser<ParseHandler>::assignExpr(InHandling inHandling, YieldHandling yieldHandl
         return yieldExpression(inHandling);
 
     bool maybeAsyncArrow = false;
-    if (tt == TOK_NAME &&
-        tokenStream.currentName() == context->names().async &&
-        !tokenStream.currentToken().nameContainsEscape())
-    {
+    if (tt == TOK_ASYNC) {
         TokenKind nextSameLine = TOK_EOF;
         if (!tokenStream.peekTokenSameLine(&nextSameLine))
             return null();
 
-        if (nextSameLine == TOK_NAME || nextSameLine == TOK_YIELD)
+        if (TokenKindIsPossibleIdentifier(nextSameLine))
             maybeAsyncArrow = true;
     }
 
@@ -7683,14 +7637,12 @@ Parser<ParseHandler>::assignExpr(InHandling inHandling, YieldHandling yieldHandl
     PossibleError possibleErrorInner(*this);
     Node lhs;
     if (maybeAsyncArrow) {
-        tokenStream.consumeKnownToken(TOK_NAME, TokenStream::Operand);
-        MOZ_ASSERT(tokenStream.currentName() == context->names().async);
-        MOZ_ASSERT(!tokenStream.currentToken().nameContainsEscape());
+        tokenStream.consumeKnownToken(TOK_ASYNC, TokenStream::Operand);
 
         TokenKind tt;
         if (!tokenStream.getToken(&tt))
             return null();
-        MOZ_ASSERT(tt == TOK_NAME || tt == TOK_YIELD);
+        MOZ_ASSERT(TokenKindIsPossibleIdentifier(tt));
 
         // Check yield validity here.
         RootedPropertyName name(context, bindingIdentifier(yieldHandling));
@@ -7759,24 +7711,18 @@ Parser<ParseHandler>::assignExpr(InHandling inHandling, YieldHandling yieldHandl
         GeneratorKind generatorKind = NotGenerator;
         FunctionAsyncKind asyncKind = SyncFunction;
 
-        if (next == TOK_NAME) {
+        if (next == TOK_ASYNC) {
             tokenStream.consumeKnownToken(next, TokenStream::Operand);
 
-            if (tokenStream.currentName() == context->names().async &&
-                !tokenStream.currentToken().nameContainsEscape())
-            {
-                TokenKind nextSameLine = TOK_EOF;
-                if (!tokenStream.peekTokenSameLine(&nextSameLine))
-                    return null();
+            TokenKind nextSameLine = TOK_EOF;
+            if (!tokenStream.peekTokenSameLine(&nextSameLine))
+                return null();
 
-                if (nextSameLine == TOK_ARROW) {
-                    tokenStream.ungetToken();
-                } else {
-                    generatorKind = StarGenerator;
-                    asyncKind = AsyncFunction;
-                }
-            } else {
+            if (nextSameLine == TOK_ARROW) {
                 tokenStream.ungetToken();
+            } else {
+                generatorKind = StarGenerator;
+                asyncKind = AsyncFunction;
             }
         }
 
@@ -8025,20 +7971,17 @@ Parser<ParseHandler>::unaryExpr(YieldHandling yieldHandling, TripledotHandling t
       }
 
       case TOK_AWAIT: {
-        if (!pc->isAsync()) {
-            // TOK_AWAIT can be returned in module, even if it's not inside
-            // async function.
-            error(JSMSG_RESERVED_ID, "await");
-            return null();
+        if (pc->isAsync()) {
+            Node kid = unaryExpr(yieldHandling, tripledotHandling, possibleError, invoked);
+            if (!kid)
+                return null();
+            pc->lastAwaitOffset = begin;
+            return newAwaitExpression(begin, kid);
         }
-
-        Node kid = unaryExpr(yieldHandling, tripledotHandling, possibleError, invoked);
-        if (!kid)
-            return null();
-        pc->lastAwaitOffset = begin;
-        return newAwaitExpression(begin, kid);
       }
 
+        MOZ_FALLTHROUGH;
+
       default: {
         Node expr = memberExpr(yieldHandling, tripledotHandling, tt, /* allowCallSyntax = */ true,
                              possibleError, invoked);
@@ -8176,7 +8119,7 @@ Parser<ParseHandler>::comprehensionFor(GeneratorKind comprehensionKind)
 
     // FIXME: Destructuring binding (bug 980828).
 
-    MUST_MATCH_TOKEN(TOK_NAME, JSMSG_NO_VARIABLE_NAME);
+    MUST_MATCH_TOKEN_FUNC(TokenKindIsPossibleIdentifier, JSMSG_NO_VARIABLE_NAME);
     RootedPropertyName name(context, tokenStream.currentName());
     if (name == context->names().let) {
         error(JSMSG_LET_COMP_BINDING);
@@ -8187,7 +8130,7 @@ Parser<ParseHandler>::comprehensionFor(GeneratorKind comprehensionKind)
     if (!lhs)
         return null();
     bool matched;
-    if (!tokenStream.matchContextualKeyword(&matched, context->names().of))
+    if (!tokenStream.matchToken(&matched, TOK_OF))
         return null();
     if (!matched) {
         error(JSMSG_OF_AFTER_FOR_NAME);
@@ -8522,9 +8465,9 @@ Parser<ParseHandler>::memberExpr(YieldHandling yieldHandling, TripledotHandling
 
         Node nextMember;
         if (tt == TOK_DOT) {
-            if (!tokenStream.getToken(&tt, TokenStream::KeywordIsName))
+            if (!tokenStream.getToken(&tt))
                 return null();
-            if (tt == TOK_NAME) {
+            if (TokenKindIsPossibleIdentifierName(tt)) {
                 PropertyName* field = tokenStream.currentName();
                 if (handler.isSuperBase(lhs) && !checkAndMarkSuperScope()) {
                     error(JSMSG_BAD_SUPERPROP, "property");
@@ -8695,46 +8638,52 @@ Parser<ParseHandler>::newName(PropertyName* name, TokenPos pos)
 
 template <typename ParseHandler>
 PropertyName*
-Parser<ParseHandler>::labelOrIdentifierReference(YieldHandling yieldHandling,
-                                                 bool yieldTokenizedAsName)
-{
-    PropertyName* ident;
-    bool isYield;
-    const Token& tok = tokenStream.currentToken();
-    if (tok.type == TOK_NAME) {
-        MOZ_ASSERT(tok.name() != context->names().yield ||
-                   tok.nameContainsEscape() ||
-                   yieldTokenizedAsName,
-                   "tokenizer should have treated unescaped 'yield' as TOK_YIELD");
-        MOZ_ASSERT_IF(yieldTokenizedAsName, tok.name() == context->names().yield);
-
-        ident = tok.name();
-        isYield = ident == context->names().yield;
-    } else {
-        MOZ_ASSERT(tok.type == TOK_YIELD && !yieldTokenizedAsName);
-
-        ident = context->names().yield;
-        isYield = true;
-    }
-
-    if (!isYield) {
-        if (pc->sc()->strict()) {
-            const char* badName = ident == context->names().let
-                                  ? "let"
-                                  : ident == context->names().static_
-                                  ? "static"
-                                  : nullptr;
-            if (badName) {
-                error(JSMSG_RESERVED_ID, badName);
-                return nullptr;
-            }
-        }
-    } else {
+Parser<ParseHandler>::checkLabelOrIdentifierReference(PropertyName* ident,
+                                                      uint32_t offset,
+                                                      YieldHandling yieldHandling)
+{
+    if (ident == context->names().yield) {
         if (yieldHandling == YieldIsKeyword ||
             pc->sc()->strict() ||
             versionNumber() >= JSVERSION_1_7)
         {
-            error(JSMSG_RESERVED_ID, "yield");
+            errorAt(offset, JSMSG_RESERVED_ID, "yield");
+            return nullptr;
+        }
+        return ident;
+    }
+
+    if (ident == context->names().await) {
+        if (awaitIsKeyword()) {
+            errorAt(offset, JSMSG_RESERVED_ID, "await");
+            return nullptr;
+        }
+        return ident;
+    }
+
+    if (IsKeyword(ident) || IsReservedWordLiteral(ident)) {
+        errorAt(offset, JSMSG_INVALID_ID, ReservedWordToCharZ(ident));
+        return nullptr;
+    }
+
+    if (IsFutureReservedWord(ident)) {
+        errorAt(offset, JSMSG_RESERVED_ID, ReservedWordToCharZ(ident));
+        return nullptr;
+    }
+
+    if (pc->sc()->strict()) {
+        if (IsStrictReservedWord(ident)) {
+            errorAt(offset, JSMSG_RESERVED_ID, ReservedWordToCharZ(ident));
+            return nullptr;
+        }
+
+        if (ident == context->names().let) {
+            errorAt(offset, JSMSG_RESERVED_ID, "let");
+            return nullptr;
+        }
+
+        if (ident == context->names().static_) {
+            errorAt(offset, JSMSG_RESERVED_ID, "static");
             return nullptr;
         }
     }
@@ -8744,52 +8693,34 @@ Parser<ParseHandler>::labelOrIdentifierReference(YieldHandling yieldHandling,
 
 template <typename ParseHandler>
 PropertyName*
-Parser<ParseHandler>::bindingIdentifier(YieldHandling yieldHandling)
+Parser<ParseHandler>::labelOrIdentifierReference(YieldHandling yieldHandling)
 {
-    PropertyName* ident;
-    bool isYield;
-    const Token& tok = tokenStream.currentToken();
-    if (tok.type == TOK_NAME) {
-        MOZ_ASSERT(tok.name() != context->names().yield || tok.nameContainsEscape(),
-                   "tokenizer should have treated unescaped 'yield' as TOK_YIELD");
-
-        ident = tok.name();
-        isYield = ident == context->names().yield;
-    } else {
-        MOZ_ASSERT(tok.type == TOK_YIELD);
+    // ES 2017 draft 12.1.1.
+    //   StringValue of IdentifierName normalizes any Unicode escape sequences
+    //   in IdentifierName hence such escapes cannot be used to write an
+    //   Identifier whose code point sequence is the same as a ReservedWord.
+    //
+    // Use PropertyName* instead of TokenKind to reflect the normalization.
 
-        ident = context->names().yield;
-        isYield = true;
-    }
+    return checkLabelOrIdentifierReference(tokenStream.currentName(), pos().begin, yieldHandling);
+}
 
-    if (!isYield) {
-        if (pc->sc()->strict()) {
-            const char* badName = ident == context->names().arguments
-                                  ? "arguments"
-                                  : ident == context->names().eval
-                                  ? "eval"
-                                  : nullptr;
-            if (badName) {
-                error(JSMSG_BAD_STRICT_ASSIGN, badName);
-                return nullptr;
-            }
+template <typename ParseHandler>
+PropertyName*
+Parser<ParseHandler>::bindingIdentifier(YieldHandling yieldHandling)
+{
+    PropertyName* ident = labelOrIdentifierReference(yieldHandling);
+    if (!ident)
+        return nullptr;
 
-            badName = ident == context->names().let
-                      ? "let"
-                      : ident == context->names().static_
-                      ? "static"
-                      : nullptr;
-            if (badName) {
-                error(JSMSG_RESERVED_ID, badName);
-                return nullptr;
-            }
+    if (pc->sc()->strict()) {
+        if (ident == context->names().arguments) {
+            error(JSMSG_BAD_STRICT_ASSIGN, "arguments");
+            return nullptr;
         }
-    } else {
-        if (yieldHandling == YieldIsKeyword ||
-            pc->sc()->strict() ||
-            versionNumber() >= JSVERSION_1_7)
-        {
-            error(JSMSG_RESERVED_ID, "yield");
+
+        if (ident == context->names().eval) {
+            error(JSMSG_BAD_STRICT_ASSIGN, "eval");
             return nullptr;
         }
     }
@@ -8970,7 +8901,7 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
                                    PropertyType* propType, MutableHandleAtom propAtom)
 {
     TokenKind ltok;
-    if (!tokenStream.getToken(&ltok, TokenStream::KeywordIsName))
+    if (!tokenStream.getToken(&ltok))
         return null();
 
     MOZ_ASSERT(ltok != TOK_RC, "caller should have handled TOK_RC");
@@ -8979,14 +8910,11 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
     bool isAsync = false;
     if (ltok == TOK_MUL) {
         isGenerator = true;
-        if (!tokenStream.getToken(&ltok, TokenStream::KeywordIsName))
+        if (!tokenStream.getToken(&ltok))
             return null();
     }
 
-    if (ltok == TOK_NAME &&
-        tokenStream.currentName() == context->names().async &&
-        !tokenStream.currentToken().nameContainsEscape())
-    {
+    if (ltok == TOK_ASYNC) {
         // AsyncMethod[Yield, Await]:
         //   async [no LineTerminator here] PropertyName[?Yield, ?Await] ...
         //
@@ -9002,16 +8930,13 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
         // ComputedPropertyName[Yield, Await]:
         //   [ ...
         TokenKind tt = TOK_EOF;
-        if (!tokenStream.peekTokenSameLine(&tt, TokenStream::KeywordIsName))
+        if (!tokenStream.getToken(&tt))
             return null();
-        if (tt == TOK_STRING || tt == TOK_NUMBER || tt == TOK_LB ||
-            tt == TOK_NAME || tt == TOK_YIELD)
-        {
+        if (tt != TOK_LP && tt != TOK_COLON && tt != TOK_RC && tt != TOK_ASSIGN) {
             isAsync = true;
-            tokenStream.consumeKnownToken(tt, TokenStream::KeywordIsName);
             ltok = tt;
         } else {
-            tokenStream.addModifierException(TokenStream::NoneIsKeywordIsName);
+            tokenStream.ungetToken();
         }
     }
 
@@ -9038,41 +8963,36 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
             return null();
         break;
 
-      case TOK_NAME: {
+      default: {
+        if (!TokenKindIsPossibleIdentifierName(ltok)) {
+            error(JSMSG_UNEXPECTED_TOKEN, "property name", TokenKindToDesc(ltok));
+            return null();
+        }
+
         propAtom.set(tokenStream.currentName());
         // Do not look for accessor syntax on generators
-        if (isGenerator || isAsync ||
-            !(propAtom.get() == context->names().get ||
-              propAtom.get() == context->names().set))
-        {
+        if (isGenerator || isAsync || !(ltok == TOK_GET || ltok == TOK_SET)) {
             propName = handler.newObjectLiteralPropertyName(propAtom, pos());
             if (!propName)
                 return null();
             break;
         }
 
-        *propType = propAtom.get() == context->names().get ? PropertyType::Getter
-                                                           : PropertyType::Setter;
+        *propType = ltok == TOK_GET ? PropertyType::Getter : PropertyType::Setter;
 
         // We have parsed |get| or |set|. Look for an accessor property
         // name next.
         TokenKind tt;
-        if (!tokenStream.peekToken(&tt, TokenStream::KeywordIsName))
+        if (!tokenStream.peekToken(&tt))
             return null();
-        if (tt == TOK_NAME) {
-            if (!checkUnescapedName())
-                return null();
-
-            tokenStream.consumeKnownToken(TOK_NAME, TokenStream::KeywordIsName);
+        if (TokenKindIsPossibleIdentifierName(tt)) {
+            tokenStream.consumeKnownToken(tt);
 
             propAtom.set(tokenStream.currentName());
             return handler.newObjectLiteralPropertyName(propAtom, pos());
         }
         if (tt == TOK_STRING) {
-            if (!checkUnescapedName())
-                return null();
-
-            tokenStream.consumeKnownToken(TOK_STRING, TokenStream::KeywordIsName);
+            tokenStream.consumeKnownToken(TOK_STRING);
 
             propAtom.set(tokenStream.currentToken().atom());
 
@@ -9086,10 +9006,7 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
             return stringLiteral();
         }
         if (tt == TOK_NUMBER) {
-            if (!checkUnescapedName())
-                return null();
-
-            tokenStream.consumeKnownToken(TOK_NUMBER, TokenStream::KeywordIsName);
+            tokenStream.consumeKnownToken(TOK_NUMBER);
 
             propAtom.set(DoubleToAtom(context, tokenStream.currentToken().number()));
             if (!propAtom.get())
@@ -9097,10 +9014,7 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
             return newNumber(tokenStream.currentToken());
         }
         if (tt == TOK_LB) {
-            if (!checkUnescapedName())
-                return null();
-
-            tokenStream.consumeKnownToken(TOK_LB, TokenStream::KeywordIsName);
+            tokenStream.consumeKnownToken(TOK_LB);
 
             return computedPropertyName(yieldHandling, propList);
         }
@@ -9109,7 +9023,6 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
         propName = handler.newObjectLiteralPropertyName(propAtom.get(), pos());
         if (!propName)
             return null();
-        tokenStream.addModifierException(TokenStream::NoneIsKeywordIsName);
         break;
       }
 
@@ -9127,10 +9040,6 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
             return null();
         break;
       }
-
-      default:
-        error(JSMSG_BAD_PROP_ID);
-        return null();
     }
 
     TokenKind tt;
@@ -9146,7 +9055,9 @@ Parser<ParseHandler>::propertyName(YieldHandling yieldHandling, Node propList,
         return propName;
     }
 
-    if (ltok == TOK_NAME && (tt == TOK_COMMA || tt == TOK_RC || tt == TOK_ASSIGN)) {
+    if (TokenKindIsPossibleIdentifierName(ltok) &&
+        (tt == TOK_COMMA || tt == TOK_RC || tt == TOK_ASSIGN))
+    {
         if (isGenerator) {
             error(JSMSG_BAD_PROP_ID);
             return null();
@@ -9214,7 +9125,7 @@ Parser<ParseHandler>::objectLiteral(YieldHandling yieldHandling, PossibleError*
     RootedAtom propAtom(context);
     for (;;) {
         TokenKind tt;
-        if (!tokenStream.getToken(&tt, TokenStream::KeywordIsName))
+        if (!tokenStream.getToken(&tt))
             return null();
         if (tt == TOK_RC)
             break;
@@ -9274,17 +9185,7 @@ Parser<ParseHandler>::objectLiteral(YieldHandling yieldHandling, PossibleError*
              * for |var {x: x, y: y} = o|, and |var o = {x, y}| as initializer
              * shorthand for |var o = {x: x, y: y}|.
              */
-            TokenKind propToken = TOK_NAME;
-            if (!tokenStream.checkForKeyword(propAtom, &propToken))
-                return null();
-
-            if (propToken != TOK_NAME && propToken != TOK_YIELD) {
-                error(JSMSG_RESERVED_ID, TokenKindToDesc(propToken));
-                return null();
-            }
-
-            Rooted<PropertyName*> name(context,
-                                       identifierReference(yieldHandling, propToken == TOK_YIELD));
+            Rooted<PropertyName*> name(context, identifierReference(yieldHandling));
             if (!name)
                 return null();
 
@@ -9299,17 +9200,7 @@ Parser<ParseHandler>::objectLiteral(YieldHandling yieldHandling, PossibleError*
              * Support, e.g., |var {x=1, y=2} = o| as destructuring shorthand
              * with default values, as per ES6 12.14.5
              */
-            TokenKind propToken = TOK_NAME;
-            if (!tokenStream.checkForKeyword(propAtom, &propToken))
-                return null();
-
-            if (propToken != TOK_NAME && propToken != TOK_YIELD) {
-                error(JSMSG_RESERVED_ID, TokenKindToDesc(propToken));
-                return null();
-            }
-
-            Rooted<PropertyName*> name(context,
-                                       identifierReference(yieldHandling, propToken == TOK_YIELD));
+            Rooted<PropertyName*> name(context, identifierReference(yieldHandling));
             if (!name)
                 return null();
 
@@ -9482,14 +9373,11 @@ Parser<ParseHandler>::tryNewTarget(Node &newTarget)
 
     if (!tokenStream.getToken(&next))
         return false;
-    if (next != TOK_NAME || tokenStream.currentName() != context->names().target) {
+    if (next != TOK_TARGET) {
         error(JSMSG_UNEXPECTED_TOKEN, "target", TokenKindToDesc(next));
         return false;
     }
 
-    if (!checkUnescapedName())
-        return false;
-
     if (!pc->sc()->allowNewTarget()) {
         errorAt(begin, JSMSG_BAD_NEWTARGET);
         return false;
@@ -9572,11 +9460,13 @@ Parser<ParseHandler>::primaryExpr(YieldHandling yieldHandling, TripledotHandling
       case TOK_STRING:
         return stringLiteral();
 
-      case TOK_YIELD:
-      case TOK_NAME: {
-        if (tokenStream.currentName() == context->names().async &&
-            !tokenStream.currentToken().nameContainsEscape())
-        {
+      default: {
+        if (!TokenKindIsPossibleIdentifier(tt)) {
+            error(JSMSG_UNEXPECTED_TOKEN, "expression", TokenKindToDesc(tt));
+            return null();
+        }
+
+        if (tt == TOK_ASYNC) {
             TokenKind nextSameLine = TOK_EOF;
             if (!tokenStream.peekTokenSameLine(&nextSameLine))
                 return null();
@@ -9648,7 +9538,7 @@ Parser<ParseHandler>::primaryExpr(YieldHandling yieldHandling, TripledotHandling
             // the enclosing code is strict mode code, any of "let", "yield",
             // or "arguments" should be prohibited.  Argument-parsing code
             // handles that.
-            if (next != TOK_NAME && next != TOK_YIELD) {
+            if (!TokenKindIsPossibleIdentifier(next)) {
                 error(JSMSG_UNEXPECTED_TOKEN, "rest argument name", TokenKindToDesc(next));
                 return null();
             }
@@ -9675,10 +9565,6 @@ Parser<ParseHandler>::primaryExpr(YieldHandling yieldHandling, TripledotHandling
         // Return an arbitrary expression node. See case TOK_RP above.
         return handler.newNullLiteral(pos());
       }
-
-      default:
-        error(JSMSG_UNEXPECTED_TOKEN, "expression", TokenKindToDesc(tt));
-        return null();
     }
 }
 
diff --git a/js/src/frontend/Parser.h b/js/src/frontend/Parser.h
index 35b9384a8..9ec862d92 100644
--- a/js/src/frontend/Parser.h
+++ b/js/src/frontend/Parser.h
@@ -734,6 +734,9 @@ class UsedNameTracker
     }
 };
 
+template <typename ParseHandler>
+class AutoAwaitIsKeyword;
+
 class ParserBase : public StrictModeGetter
 {
   private:
@@ -783,7 +786,13 @@ class ParserBase : public StrictModeGetter
     /* Unexpected end of input, i.e. TOK_EOF not at top-level. */
     bool isUnexpectedEOF_:1;
 
+    bool awaitIsKeyword_:1;
+
   public:
+    bool awaitIsKeyword() const {
+      return awaitIsKeyword_;
+    }
+
     ParserBase(ExclusiveContext* cx, LifoAlloc& alloc, const ReadOnlyCompileOptions& options,
                const char16_t* chars, size_t length, bool foldConstants,
                UsedNameTracker& usedNames, Parser<SyntaxParseHandler>* syntaxParser,
@@ -998,6 +1007,9 @@ class Parser final : public ParserBase, private JS::AutoGCRooter
            Parser<SyntaxParseHandler>* syntaxParser, LazyScript* lazyOuterFunction);
     ~Parser();
 
+    friend class AutoAwaitIsKeyword<ParseHandler>;
+    void setAwaitIsKeyword(bool isKeyword);
+
     bool checkOptions();
 
     // A Parser::Mark is the extension of the LifoAlloc::Mark to the entire
@@ -1047,8 +1059,6 @@ class Parser final : public ParserBase, private JS::AutoGCRooter
 
     void trace(JSTracer* trc);
 
-    bool checkUnescapedName();
-
   private:
     Parser* thisForCtor() { return this; }
 
@@ -1321,17 +1331,18 @@ class Parser final : public ParserBase, private JS::AutoGCRooter
     Node classDefinition(YieldHandling yieldHandling, ClassContext classContext,
                          DefaultHandling defaultHandling);
 
-    PropertyName* labelOrIdentifierReference(YieldHandling yieldHandling,
-                                             bool yieldTokenizedAsName);
+    PropertyName* checkLabelOrIdentifierReference(PropertyName* ident,
+                                                  uint32_t offset,
+                                                  YieldHandling yieldHandling);
+
+    PropertyName* labelOrIdentifierReference(YieldHandling yieldHandling);
 
     PropertyName* labelIdentifier(YieldHandling yieldHandling) {
-        return labelOrIdentifierReference(yieldHandling, false);
+        return labelOrIdentifierReference(yieldHandling);
     }
 
-    PropertyName* identifierReference(YieldHandling yieldHandling,
-                                      bool yieldTokenizedAsName = false)
-    {
-        return labelOrIdentifierReference(yieldHandling, yieldTokenizedAsName);
+    PropertyName* identifierReference(YieldHandling yieldHandling) {
+        return labelOrIdentifierReference(yieldHandling);
     }
 
     PropertyName* importedBinding() {
@@ -1455,6 +1466,25 @@ class Parser final : public ParserBase, private JS::AutoGCRooter
     bool asmJS(Node list);
 };
 
+template <typename ParseHandler>
+class MOZ_STACK_CLASS AutoAwaitIsKeyword
+{
+  private:
+    Parser<ParseHandler>* parser_;
+    bool oldAwaitIsKeyword_;
+
+  public:
+    AutoAwaitIsKeyword(Parser<ParseHandler>* parser, bool awaitIsKeyword) {
+        parser_ = parser;
+        oldAwaitIsKeyword_ = parser_->awaitIsKeyword_;
+        parser_->setAwaitIsKeyword(awaitIsKeyword);
+    }
+
+    ~AutoAwaitIsKeyword() {
+        parser_->setAwaitIsKeyword(oldAwaitIsKeyword_);
+    }
+};
+
 } /* namespace frontend */
 } /* namespace js */
 
diff --git a/js/src/frontend/ReservedWords.h b/js/src/frontend/ReservedWords.h
new file mode 100644
index 000000000..27f5b11c1
--- /dev/null
+++ b/js/src/frontend/ReservedWords.h
@@ -0,0 +1,81 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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/. */
+
+/* A higher-order macro for enumerating reserved word tokens. */
+
+#ifndef vm_ReservedWords_h
+#define vm_ReservedWords_h
+
+#define FOR_EACH_JAVASCRIPT_RESERVED_WORD(macro) \
+    macro(false, false_, TOK_FALSE) \
+    macro(true, true_, TOK_TRUE) \
+    macro(null, null, TOK_NULL) \
+    \
+    /* Keywords. */ \
+    macro(break, break_, TOK_BREAK) \
+    macro(case, case_, TOK_CASE) \
+    macro(catch, catch_, TOK_CATCH) \
+    macro(const, const_, TOK_CONST) \
+    macro(continue, continue_, TOK_CONTINUE) \
+    macro(debugger, debugger, TOK_DEBUGGER) \
+    macro(default, default_, TOK_DEFAULT) \
+    macro(delete, delete_, TOK_DELETE) \
+    macro(do, do_, TOK_DO) \
+    macro(else, else_, TOK_ELSE) \
+    macro(finally, finally_, TOK_FINALLY) \
+    macro(for, for_, TOK_FOR) \
+    macro(function, function, TOK_FUNCTION) \
+    macro(if, if_, TOK_IF) \
+    macro(in, in, TOK_IN) \
+    macro(instanceof, instanceof, TOK_INSTANCEOF) \
+    macro(new, new_, TOK_NEW) \
+    macro(return, return_, TOK_RETURN) \
+    macro(switch, switch_, TOK_SWITCH) \
+    macro(this, this_, TOK_THIS) \
+    macro(throw, throw_, TOK_THROW) \
+    macro(try, try_, TOK_TRY) \
+    macro(typeof, typeof_, TOK_TYPEOF) \
+    macro(var, var, TOK_VAR) \
+    macro(void, void_, TOK_VOID) \
+    macro(while, while_, TOK_WHILE) \
+    macro(with, with, TOK_WITH) \
+    macro(import, import, TOK_IMPORT) \
+    macro(export, export_, TOK_EXPORT) \
+    macro(class, class_, TOK_CLASS) \
+    macro(extends, extends, TOK_EXTENDS) \
+    macro(super, super, TOK_SUPER) \
+    \
+    /* Future reserved words. */ \
+    macro(enum, enum_, TOK_ENUM) \
+    \
+    /* Future reserved words, but only in strict mode. */ \
+    macro(implements, implements, TOK_IMPLEMENTS) \
+    macro(interface, interface, TOK_INTERFACE) \
+    macro(package, package, TOK_PACKAGE) \
+    macro(private, private_, TOK_PRIVATE) \
+    macro(protected, protected_, TOK_PROTECTED) \
+    macro(public, public_, TOK_PUBLIC) \
+    \
+    /* Contextual keywords. */ \
+    macro(as, as, TOK_AS) \
+    macro(async, async, TOK_ASYNC) \
+    macro(await, await, TOK_AWAIT) \
+    macro(each, each, TOK_EACH) \
+    macro(from, from, TOK_FROM) \
+    macro(get, get, TOK_GET) \
+    macro(let, let, TOK_LET) \
+    macro(of, of, TOK_OF) \
+    macro(set, set, TOK_SET) \
+    macro(static, static_, TOK_STATIC) \
+    macro(target, target, TOK_TARGET) \
+    /* \
+     * Yield is a token inside function*.  Outside of a function*, it is a \
+     * future reserved word in strict mode, but a keyword in JS1.7 even \
+     * when strict.  Punt logic to parser. \
+     */ \
+    macro(yield, yield, TOK_YIELD)
+
+#endif /* vm_ReservedWords_h */
diff --git a/js/src/frontend/TokenKind.h b/js/src/frontend/TokenKind.h
index 6f22d78e5..98f23fec8 100644
--- a/js/src/frontend/TokenKind.h
+++ b/js/src/frontend/TokenKind.h
@@ -81,9 +81,12 @@
     \
     macro(REGEXP,       "regular expression literal") \
     macro(TRUE,         "boolean literal 'true'") \
+    range(RESERVED_WORD_LITERAL_FIRST, TRUE) \
     macro(FALSE,        "boolean literal 'false'") \
     macro(NULL,         "null literal") \
+    range(RESERVED_WORD_LITERAL_LAST, NULL) \
     macro(THIS,         "keyword 'this'") \
+    range(KEYWORD_FIRST, THIS) \
     macro(FUNCTION,     "keyword 'function'") \
     macro(IF,           "keyword 'if'") \
     macro(ELSE,         "keyword 'else'") \
@@ -106,16 +109,43 @@
     macro(FINALLY,      "keyword 'finally'") \
     macro(THROW,        "keyword 'throw'") \
     macro(DEBUGGER,     "keyword 'debugger'") \
-    macro(YIELD,        "keyword 'yield'") \
-    macro(AWAIT,        "keyword 'await'") \
     macro(EXPORT,       "keyword 'export'") \
     macro(IMPORT,       "keyword 'import'") \
     macro(CLASS,        "keyword 'class'") \
     macro(EXTENDS,      "keyword 'extends'") \
     macro(SUPER,        "keyword 'super'") \
-    macro(RESERVED,     "reserved keyword") \
-    /* reserved keywords in strict mode */ \
-    macro(STRICT_RESERVED, "reserved keyword") \
+    range(KEYWORD_LAST, SUPER) \
+    \
+    /* contextual keywords */ \
+    macro(AS,           "'as'") \
+    range(CONTEXTUAL_KEYWORD_FIRST, AS) \
+    macro(ASYNC,        "'async'") \
+    macro(AWAIT,        "'await'") \
+    macro(EACH,         "'each'") \
+    macro(FROM,         "'from'") \
+    macro(GET,          "'get'") \
+    macro(LET,          "'let'") \
+    macro(OF,           "'of'") \
+    macro(SET,          "'set'") \
+    macro(STATIC,       "'static'") \
+    macro(TARGET,       "'target'") \
+    macro(YIELD,        "'yield'") \
+    range(CONTEXTUAL_KEYWORD_LAST, YIELD) \
+    \
+    /* future reserved words */ \
+    macro(ENUM,         "reserved word 'enum'") \
+    range(FUTURE_RESERVED_KEYWORD_FIRST, ENUM) \
+    range(FUTURE_RESERVED_KEYWORD_LAST, ENUM) \
+    \
+    /* reserved words in strict mode */ \
+    macro(IMPLEMENTS,   "reserved word 'implements'") \
+    range(STRICT_RESERVED_KEYWORD_FIRST, IMPLEMENTS) \
+    macro(INTERFACE,    "reserved word 'interface'") \
+    macro(PACKAGE,      "reserved word 'package'") \
+    macro(PRIVATE,      "reserved word 'private'") \
+    macro(PROTECTED,    "reserved word 'protected'") \
+    macro(PUBLIC,       "reserved word 'public'") \
+    range(STRICT_RESERVED_KEYWORD_LAST, PUBLIC) \
     \
     /* \
      * The following token types occupy contiguous ranges to enable easy \
@@ -149,7 +179,9 @@
     range(RELOP_LAST, GE) \
     \
     macro(INSTANCEOF,   "keyword 'instanceof'") \
+    range(KEYWORD_BINOP_FIRST, INSTANCEOF) \
     macro(IN,           "keyword 'in'") \
+    range(KEYWORD_BINOP_LAST, IN) \
     \
     /* Shift ops, per TokenKindIsShift. */ \
     macro(LSH,          "'<<'") \
@@ -168,7 +200,9 @@
     \
     /* Unary operation tokens. */ \
     macro(TYPEOF,       "keyword 'typeof'") \
+    range(KEYWORD_UNOP_FIRST, TYPEOF) \
     macro(VOID,         "keyword 'void'") \
+    range(KEYWORD_UNOP_LAST, VOID) \
     macro(NOT,          "'!'") \
     macro(BITNOT,       "'~'") \
     \
@@ -239,6 +273,61 @@ TokenKindIsAssignment(TokenKind tt)
     return TOK_ASSIGNMENT_START <= tt && tt <= TOK_ASSIGNMENT_LAST;
 }
 
+inline MOZ_MUST_USE bool
+TokenKindIsKeyword(TokenKind tt)
+{
+    return (TOK_KEYWORD_FIRST <= tt && tt <= TOK_KEYWORD_LAST) ||
+           (TOK_KEYWORD_BINOP_FIRST <= tt && tt <= TOK_KEYWORD_BINOP_LAST) ||
+           (TOK_KEYWORD_UNOP_FIRST <= tt && tt <= TOK_KEYWORD_UNOP_LAST);
+}
+
+inline MOZ_MUST_USE bool
+TokenKindIsContextualKeyword(TokenKind tt)
+{
+    return TOK_CONTEXTUAL_KEYWORD_FIRST <= tt && tt <= TOK_CONTEXTUAL_KEYWORD_LAST;
+}
+
+inline MOZ_MUST_USE bool
+TokenKindIsFutureReservedWord(TokenKind tt)
+{
+    return TOK_FUTURE_RESERVED_KEYWORD_FIRST <= tt && tt <= TOK_FUTURE_RESERVED_KEYWORD_LAST;
+}
+
+inline MOZ_MUST_USE bool
+TokenKindIsStrictReservedWord(TokenKind tt)
+{
+    return TOK_STRICT_RESERVED_KEYWORD_FIRST <= tt && tt <= TOK_STRICT_RESERVED_KEYWORD_LAST;
+}
+
+inline MOZ_MUST_USE bool
+TokenKindIsReservedWordLiteral(TokenKind tt)
+{
+    return TOK_RESERVED_WORD_LITERAL_FIRST <= tt && tt <= TOK_RESERVED_WORD_LITERAL_LAST;
+}
+
+inline MOZ_MUST_USE bool
+TokenKindIsReservedWord(TokenKind tt)
+{
+    return TokenKindIsKeyword(tt) ||
+           TokenKindIsFutureReservedWord(tt) ||
+           TokenKindIsReservedWordLiteral(tt);
+}
+
+inline MOZ_MUST_USE bool
+TokenKindIsPossibleIdentifier(TokenKind tt)
+{
+    return tt == TOK_NAME ||
+           TokenKindIsContextualKeyword(tt) ||
+           TokenKindIsStrictReservedWord(tt);
+}
+
+inline MOZ_MUST_USE bool
+TokenKindIsPossibleIdentifierName(TokenKind tt)
+{
+    return TokenKindIsPossibleIdentifier(tt) ||
+           TokenKindIsReservedWord(tt);
+}
+
 } // namespace frontend
 } // namespace js
 
diff --git a/js/src/frontend/TokenStream.cpp b/js/src/frontend/TokenStream.cpp
index 76ea7e821..b8623d545 100644
--- a/js/src/frontend/TokenStream.cpp
+++ b/js/src/frontend/TokenStream.cpp
@@ -24,10 +24,10 @@
 #include "jsnum.h"
 
 #include "frontend/BytecodeCompiler.h"
+#include "frontend/ReservedWords.h"
 #include "js/CharacterEncoding.h"
 #include "js/UniquePtr.h"
 #include "vm/HelperThreads.h"
-#include "vm/Keywords.h"
 #include "vm/StringBuffer.h"
 #include "vm/Unicode.h"
 
@@ -40,65 +40,65 @@ using mozilla::PodAssign;
 using mozilla::PodCopy;
 using mozilla::PodZero;
 
-struct KeywordInfo {
-    const char* chars;         // C string with keyword text
+struct ReservedWordInfo {
+    const char* chars;         // C string with reserved word text
     TokenKind   tokentype;
 };
 
-static const KeywordInfo keywords[] = {
-#define KEYWORD_INFO(keyword, name, type) \
-    {js_##keyword##_str, type},
-    FOR_EACH_JAVASCRIPT_KEYWORD(KEYWORD_INFO)
-#undef KEYWORD_INFO
+static const ReservedWordInfo reservedWords[] = {
+#define RESERVED_WORD_INFO(word, name, type) \
+    {js_##word##_str, type},
+    FOR_EACH_JAVASCRIPT_RESERVED_WORD(RESERVED_WORD_INFO)
+#undef RESERVED_WORD_INFO
 };
 
-// Returns a KeywordInfo for the specified characters, or nullptr if the string
-// is not a keyword.
+// Returns a ReservedWordInfo for the specified characters, or nullptr if the
+// string is not a reserved word.
 template <typename CharT>
-static const KeywordInfo*
-FindKeyword(const CharT* s, size_t length)
+static const ReservedWordInfo*
+FindReservedWord(const CharT* s, size_t length)
 {
     MOZ_ASSERT(length != 0);
 
     size_t i;
-    const KeywordInfo* kw;
+    const ReservedWordInfo* rw;
     const char* chars;
 
-#define JSKW_LENGTH()           length
-#define JSKW_AT(column)         s[column]
-#define JSKW_GOT_MATCH(index)   i = (index); goto got_match;
-#define JSKW_TEST_GUESS(index)  i = (index); goto test_guess;
-#define JSKW_NO_MATCH()         goto no_match;
-#include "jsautokw.h"
-#undef JSKW_NO_MATCH
-#undef JSKW_TEST_GUESS
-#undef JSKW_GOT_MATCH
-#undef JSKW_AT
-#undef JSKW_LENGTH
+#define JSRW_LENGTH()           length
+#define JSRW_AT(column)         s[column]
+#define JSRW_GOT_MATCH(index)   i = (index); goto got_match;
+#define JSRW_TEST_GUESS(index)  i = (index); goto test_guess;
+#define JSRW_NO_MATCH()         goto no_match;
+#include "frontend/ReservedWordsGenerated.h"
+#undef JSRW_NO_MATCH
+#undef JSRW_TEST_GUESS
+#undef JSRW_GOT_MATCH
+#undef JSRW_AT
+#undef JSRW_LENGTH
 
   got_match:
-    return &keywords[i];
+    return &reservedWords[i];
 
   test_guess:
-    kw = &keywords[i];
-    chars = kw->chars;
+    rw = &reservedWords[i];
+    chars = rw->chars;
     do {
         if (*s++ != (unsigned char)(*chars++))
             goto no_match;
     } while (--length != 0);
-    return kw;
+    return rw;
 
   no_match:
     return nullptr;
 }
 
-static const KeywordInfo*
-FindKeyword(JSLinearString* str)
+static const ReservedWordInfo*
+FindReservedWord(JSLinearString* str)
 {
     JS::AutoCheckCannotGC nogc;
     return str->hasLatin1Chars()
-           ? FindKeyword(str->latin1Chars(nogc), str->length())
-           : FindKeyword(str->twoByteChars(nogc), str->length());
+           ? FindReservedWord(str->latin1Chars(nogc), str->length())
+           : FindReservedWord(str->twoByteChars(nogc), str->length());
 }
 
 template <typename CharT>
@@ -188,7 +188,68 @@ frontend::IsIdentifier(const char16_t* chars, size_t length)
 bool
 frontend::IsKeyword(JSLinearString* str)
 {
-    return FindKeyword(str) != nullptr;
+    if (const ReservedWordInfo* rw = FindReservedWord(str))
+        return TokenKindIsKeyword(rw->tokentype);
+
+    return false;
+}
+
+bool
+frontend::IsFutureReservedWord(JSLinearString* str)
+{
+    if (const ReservedWordInfo* rw = FindReservedWord(str))
+        return TokenKindIsFutureReservedWord(rw->tokentype);
+
+    return false;
+}
+
+bool
+frontend::IsStrictReservedWord(JSLinearString* str)
+{
+    if (const ReservedWordInfo* rw = FindReservedWord(str))
+        return TokenKindIsStrictReservedWord(rw->tokentype);
+
+    return false;
+}
+
+bool
+frontend::IsReservedWordLiteral(JSLinearString* str)
+{
+    if (const ReservedWordInfo* rw = FindReservedWord(str))
+        return TokenKindIsReservedWordLiteral(rw->tokentype);
+
+    return false;
+}
+
+const char*
+frontend::ReservedWordToCharZ(PropertyName* str)
+{
+    const ReservedWordInfo* rw = FindReservedWord(str);
+    if (rw == nullptr)
+        return nullptr;
+
+    switch (rw->tokentype) {
+#define EMIT_CASE(word, name, type) case type: return js_##word##_str;
+      FOR_EACH_JAVASCRIPT_RESERVED_WORD(EMIT_CASE)
+#undef EMIT_CASE
+      default:
+        MOZ_ASSERT_UNREACHABLE("Not a reserved word PropertyName.");
+    }
+    return nullptr;
+}
+
+PropertyName*
+TokenStream::reservedWordToPropertyName(TokenKind tt) const
+{
+    MOZ_ASSERT(tt != TOK_NAME);
+    switch (tt) {
+#define EMIT_CASE(word, name, type) case type: return cx->names().name;
+      FOR_EACH_JAVASCRIPT_RESERVED_WORD(EMIT_CASE)
+#undef EMIT_CASE
+      default:
+        MOZ_ASSERT_UNREACHABLE("Not a reserved word TokenKind.");
+    }
+    return nullptr;
 }
 
 TokenStream::SourceCoords::SourceCoords(ExclusiveContext* cx, uint32_t ln)
@@ -1169,38 +1230,6 @@ TokenStream::putIdentInTokenbuf(const char16_t* identStart)
     return true;
 }
 
-bool
-TokenStream::checkForKeyword(const KeywordInfo* kw, TokenKind* ttp)
-{
-    if (!awaitIsKeyword && kw->tokentype == TOK_AWAIT) {
-        if (ttp)
-            *ttp = TOK_NAME;
-        return true;
-    }
-
-    if (kw->tokentype == TOK_RESERVED) {
-        error(JSMSG_RESERVED_ID, kw->chars);
-        return false;
-    }
-
-    if (kw->tokentype == TOK_STRICT_RESERVED)
-        return reportStrictModeError(JSMSG_RESERVED_ID, kw->chars);
-
-    // Working keyword.
-    *ttp = kw->tokentype;
-    return true;
-}
-
-bool
-TokenStream::checkForKeyword(JSAtom* atom, TokenKind* ttp)
-{
-    const KeywordInfo* kw = FindKeyword(atom);
-    if (!kw)
-        return true;
-
-    return checkForKeyword(kw, ttp);
-}
-
 enum FirstCharKind {
     // A char16_t has the 'OneChar' kind if it, by itself, constitutes a valid
     // token that cannot also be a prefix of a longer token.  E.g. ';' has the
@@ -1424,36 +1453,18 @@ TokenStream::getTokenInternal(TokenKind* ttp, Modifier modifier)
             length = userbuf.addressOfNextRawChar() - identStart;
         }
 
-        // Represent keywords as keyword tokens unless told otherwise.
-        if (modifier != KeywordIsName) {
-            if (const KeywordInfo* kw = FindKeyword(chars, length)) {
-                // That said, keywords can't contain escapes.  (Contexts where
-                // keywords are treated as names, that also sometimes treat
-                // keywords as keywords, must manually check this requirement.)
-                // There are two exceptions
-                // 1) StrictReservedWords: These keywords need to be treated as
-                //    names in non-strict mode.
-                // 2) yield is also treated as a name if it contains an escape
-                //    sequence. The parser must handle this case separately.
-                if (hadUnicodeEscape && !(
-                        (kw->tokentype == TOK_STRICT_RESERVED && !strictMode()) ||
-                         kw->tokentype == TOK_YIELD))
-                {
-                    reportError(JSMSG_ESCAPED_KEYWORD);
-                    goto error;
-                }
-
-                tp->type = TOK_NAME;
-                if (!checkForKeyword(kw, &tp->type))
-                    goto error;
-                if (tp->type != TOK_NAME && !hadUnicodeEscape)
-                    goto out;
+        // Represent reserved words as reserved word tokens.
+        if (!hadUnicodeEscape) {
+            if (const ReservedWordInfo* rw = FindReservedWord(chars, length)) {
+                tp->type = rw->tokentype;
+                goto out;
             }
         }
 
         JSAtom* atom = AtomizeChars(cx, chars, length);
-        if (!atom)
+        if (!atom) {
             goto error;
+        }
         tp->type = TOK_NAME;
         tp->setName(atom->asPropertyName());
         goto out;
diff --git a/js/src/frontend/TokenStream.h b/js/src/frontend/TokenStream.h
index e0119c83d..e92de4b03 100644
--- a/js/src/frontend/TokenStream.h
+++ b/js/src/frontend/TokenStream.h
@@ -26,14 +26,13 @@
 #include "js/UniquePtr.h"
 #include "js/Vector.h"
 #include "vm/RegExpObject.h"
+#include "vm/String.h"
 
 struct KeywordInfo;
 
 namespace js {
 namespace frontend {
 
-class AutoAwaitIsKeyword;
-
 struct TokenPos {
     uint32_t    begin;  // Offset of the token's first char.
     uint32_t    end;    // Offset of 1 past the token's last char.
@@ -120,9 +119,6 @@ struct Token
         // TOK_DIV.
         Operand,
 
-        // Treat keywords as names by returning TOK_NAME.
-        KeywordIsName,
-
         // Treat subsequent characters as the tail of a template literal, after
         // a template substitution, beginning with a "}", continuing with zero
         // or more template literal characters, and ending with either "${" or
@@ -164,10 +160,6 @@ struct Token
         // If a semicolon is inserted automatically, the next token is already
         // gotten with None, but we expect Operand.
         OperandIsNone,
-
-        // If name of method definition is `get` or `set`, the next token is
-        // already gotten with KeywordIsName, but we expect None.
-        NoneIsKeywordIsName,
     };
     friend class TokenStream;
 
@@ -224,11 +216,6 @@ struct Token
         return u.name->JSAtom::asPropertyName(); // poor-man's type verification
     }
 
-    bool nameContainsEscape() const {
-        PropertyName* n = name();
-        return pos.begin + n->length() != pos.end;
-    }
-
     JSAtom* atom() const {
         MOZ_ASSERT(type == TOK_STRING ||
                    type == TOK_TEMPLATE_HEAD ||
@@ -254,10 +241,22 @@ struct Token
 };
 
 class CompileError : public JSErrorReport {
-public:
+  public:
     void throwError(JSContext* cx);
 };
 
+extern const char*
+ReservedWordToCharZ(PropertyName* str);
+
+extern MOZ_MUST_USE bool
+IsFutureReservedWord(JSLinearString* str);
+
+extern MOZ_MUST_USE bool
+IsReservedWordLiteral(JSLinearString* str);
+
+extern MOZ_MUST_USE bool
+IsStrictReservedWord(JSLinearString* str);
+
 // Ideally, tokenizing would be entirely independent of context.  But the
 // strict mode flag, which is in SharedContext, affects tokenizing, and
 // TokenStream needs to see it.
@@ -344,25 +343,26 @@ class MOZ_STACK_CLASS TokenStream
     JSVersion versionNumber() const { return VersionNumber(options().version); }
     JSVersion versionWithFlags() const { return options().version; }
 
+  private:
+    PropertyName* reservedWordToPropertyName(TokenKind tt) const;
+
+  public:
     PropertyName* currentName() const {
-        if (isCurrentTokenType(TOK_YIELD))
-            return cx->names().yield;
-        MOZ_ASSERT(isCurrentTokenType(TOK_NAME));
-        return currentToken().name();
+        if (isCurrentTokenType(TOK_NAME)) {
+            return currentToken().name();
+        }
+
+        MOZ_ASSERT(TokenKindIsPossibleIdentifierName(currentToken().type));
+        return reservedWordToPropertyName(currentToken().type);
     }
 
     PropertyName* nextName() const {
-        if (nextToken().type == TOK_YIELD)
-            return cx->names().yield;
-        MOZ_ASSERT(nextToken().type == TOK_NAME);
-        return nextToken().name();
-    }
+        if (nextToken().type != TOK_NAME) {
+            return nextToken().name();
+        }
 
-    bool nextNameContainsEscape() const {
-        if (nextToken().type == TOK_YIELD)
-            return false;
-        MOZ_ASSERT(nextToken().type == TOK_NAME);
-        return nextToken().nameContainsEscape();
+        MOZ_ASSERT(TokenKindIsPossibleIdentifierName(nextToken().type));
+        return reservedWordToPropertyName(nextToken().type);
     }
 
     bool isCurrentTokenAssignment() const {
@@ -498,9 +498,6 @@ class MOZ_STACK_CLASS TokenStream
         {}
     };
 
-    bool awaitIsKeyword = false;
-    friend class AutoAwaitIsKeyword;
-
     uint32_t invalidTemplateEscapeOffset = 0;
     InvalidEscapeType invalidTemplateEscapeType = InvalidEscapeType::None;
 
@@ -508,14 +505,12 @@ class MOZ_STACK_CLASS TokenStream
     typedef Token::Modifier Modifier;
     static constexpr Modifier None = Token::None;
     static constexpr Modifier Operand = Token::Operand;
-    static constexpr Modifier KeywordIsName = Token::KeywordIsName;
     static constexpr Modifier TemplateTail = Token::TemplateTail;
 
     typedef Token::ModifierException ModifierException;
     static constexpr ModifierException NoException = Token::NoException;
     static constexpr ModifierException NoneIsOperand = Token::NoneIsOperand;
     static constexpr ModifierException OperandIsNone = Token::OperandIsNone;
-    static constexpr ModifierException NoneIsKeywordIsName = Token::NoneIsKeywordIsName;
 
     void addModifierException(ModifierException modifierException) {
 #ifdef DEBUG
@@ -544,10 +539,6 @@ class MOZ_STACK_CLASS TokenStream
             MOZ_ASSERT(next.type != TOK_DIV && next.type != TOK_REGEXP,
                        "next token requires contextual specifier to be parsed unambiguously");
             break;
-          case NoneIsKeywordIsName:
-            MOZ_ASSERT(next.modifier == KeywordIsName);
-            MOZ_ASSERT(next.type != TOK_NAME);
-            break;
           default:
             MOZ_CRASH("unexpected modifier exception");
         }
@@ -574,12 +565,6 @@ class MOZ_STACK_CLASS TokenStream
                 return;
         }
 
-        if (lookaheadToken.modifierException == NoneIsKeywordIsName) {
-            // getToken() permissibly following getToken(KeywordIsName).
-            if (modifier == None && lookaheadToken.modifier == KeywordIsName)
-                return;
-        }
-
         MOZ_ASSERT_UNREACHABLE("this token was previously looked up with a "
                                "different modifier, potentially making "
                                "tokenization non-deterministic");
@@ -714,36 +699,6 @@ class MOZ_STACK_CLASS TokenStream
         MOZ_ALWAYS_TRUE(matched);
     }
 
-    // Like matchToken(..., TOK_NAME) but further matching the name token only
-    // if it has the given characters, without containing escape sequences.
-    // If the name token has the given characters yet *does* contain an escape,
-    // a syntax error will be reported.
-    //
-    // This latter behavior makes this method unsuitable for use in any context
-    // where ASI might occur.  In such places, an escaped "contextual keyword"
-    // on a new line is the start of an ExpressionStatement, not a continuation
-    // of a StatementListItem (or ImportDeclaration or ExportDeclaration, in
-    // modules).
-    MOZ_MUST_USE bool matchContextualKeyword(bool* matchedp, Handle<PropertyName*> keyword,
-                                             Modifier modifier = None)
-    {
-        TokenKind token;
-        if (!getToken(&token, modifier))
-            return false;
-        if (token == TOK_NAME && currentToken().name() == keyword) {
-            if (currentToken().nameContainsEscape()) {
-                reportError(JSMSG_ESCAPED_KEYWORD);
-                return false;
-            }
-
-            *matchedp = true;
-        } else {
-            *matchedp = false;
-            ungetToken();
-        }
-        return true;
-    }
-
     MOZ_MUST_USE bool nextTokenEndsExpr(bool* endsExpr) {
         TokenKind tt;
         if (!peekToken(&tt))
@@ -809,19 +764,6 @@ class MOZ_STACK_CLASS TokenStream
         return sourceMapURL_.get();
     }
 
-    // If |atom| is not a keyword in this version, return true with *ttp
-    // unchanged.
-    //
-    // If it is a reserved word in this version and strictness mode, and thus
-    // can't be present in correct code, report a SyntaxError and return false.
-    //
-    // If it is a keyword, like "if", return true with the keyword's TokenKind
-    // in *ttp.
-    MOZ_MUST_USE bool checkForKeyword(JSAtom* atom, TokenKind* ttp);
-
-    // Same semantics as above, but for the provided keyword.
-    MOZ_MUST_USE bool checkForKeyword(const KeywordInfo* kw, TokenKind* ttp);
-
     // This class maps a userbuf offset (which is 0-indexed) to a line number
     // (which is 1-indexed) and a column index (which is 0-indexed).
     class SourceCoords
@@ -1103,25 +1045,6 @@ class MOZ_STACK_CLASS TokenStream
     StrictModeGetter*   strictModeGetter;  // used to test for strict mode
 };
 
-class MOZ_STACK_CLASS AutoAwaitIsKeyword
-{
-private:
-    TokenStream* ts_;
-    bool oldAwaitIsKeyword_;
-
-public:
-    AutoAwaitIsKeyword(TokenStream* ts, bool awaitIsKeyword) {
-        ts_ = ts;
-        oldAwaitIsKeyword_ = ts_->awaitIsKeyword;
-        ts_->awaitIsKeyword = awaitIsKeyword;
-    }
-
-    ~AutoAwaitIsKeyword() {
-        ts_->awaitIsKeyword = oldAwaitIsKeyword_;
-        ts_ = nullptr;
-    }
-};
-
 extern const char*
 TokenKindToDesc(TokenKind tt);
 
diff --git a/js/src/jit-test/tests/modules/export-declaration.js b/js/src/jit-test/tests/modules/export-declaration.js
index 3c4a9b735..48d1072bf 100644
--- a/js/src/jit-test/tests/modules/export-declaration.js
+++ b/js/src/jit-test/tests/modules/export-declaration.js
@@ -403,9 +403,7 @@ assertThrowsInstanceOf(function() {
     parseAsModule("export {,} from 'a'");
 }, SyntaxError);
 
-assertThrowsInstanceOf(function() {
-    parseAsModule("export { true as a } from 'b'");
-}, SyntaxError);
+parseAsModule("export { true as a } from 'b'");
 
 assertThrowsInstanceOf(function () {
     parseAsModule("export { a } from 'b' f();");
diff --git a/js/src/js.msg b/js/src/js.msg
index 495e3bfad..ce039cbc8 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -265,6 +265,7 @@ MSG_DEF(JSMSG_IMPORT_DECL_AT_TOP_LEVEL, 0, JSEXN_SYNTAXERR, "import declarations
 MSG_DEF(JSMSG_OF_AFTER_FOR_LOOP_DECL,  0, JSEXN_SYNTAXERR, "a declaration in the head of a for-of loop can't have an initializer")
 MSG_DEF(JSMSG_IN_AFTER_LEXICAL_FOR_DECL,0,JSEXN_SYNTAXERR, "a lexical declaration in the head of a for-in loop can't have an initializer")
 MSG_DEF(JSMSG_INVALID_FOR_IN_DECL_WITH_INIT,0,JSEXN_SYNTAXERR,"for-in loop head declarations may not have initializers")
+MSG_DEF(JSMSG_INVALID_ID,              1, JSEXN_SYNTAXERR, "{0} is an invalid identifier")
 MSG_DEF(JSMSG_LABEL_NOT_FOUND,         0, JSEXN_SYNTAXERR, "label not found")
 MSG_DEF(JSMSG_LET_COMP_BINDING,        0, JSEXN_SYNTAXERR, "'let' is not a valid name for a comprehension variable")
 MSG_DEF(JSMSG_LEXICAL_DECL_NOT_IN_BLOCK,   1, JSEXN_SYNTAXERR, "{0} declaration not directly within block")
diff --git a/js/src/jsatom.cpp b/js/src/jsatom.cpp
index 2a3c58638..280ec3e9c 100644
--- a/js/src/jsatom.cpp
+++ b/js/src/jsatom.cpp
@@ -54,41 +54,9 @@ FOR_EACH_COMMON_PROPERTYNAME(CONST_CHAR_STR)
 #undef CONST_CHAR_STR
 
 /* Constant strings that are not atomized. */
-const char js_break_str[]           = "break";
-const char js_case_str[]            = "case";
-const char js_catch_str[]           = "catch";
-const char js_class_str[]           = "class";
-const char js_const_str[]           = "const";
-const char js_continue_str[]        = "continue";
-const char js_debugger_str[]        = "debugger";
-const char js_default_str[]         = "default";
-const char js_do_str[]              = "do";
-const char js_else_str[]            = "else";
-const char js_enum_str[]            = "enum";
-const char js_export_str[]          = "export";
-const char js_extends_str[]         = "extends";
-const char js_finally_str[]         = "finally";
-const char js_for_str[]             = "for";
 const char js_getter_str[]          = "getter";
-const char js_if_str[]              = "if";
-const char js_implements_str[]      = "implements";
-const char js_import_str[]          = "import";
-const char js_in_str[]              = "in";
-const char js_instanceof_str[]      = "instanceof";
-const char js_interface_str[]       = "interface";
-const char js_package_str[]         = "package";
-const char js_private_str[]         = "private";
-const char js_protected_str[]       = "protected";
-const char js_public_str[]          = "public";
 const char js_send_str[]            = "send";
 const char js_setter_str[]          = "setter";
-const char js_switch_str[]          = "switch";
-const char js_this_str[]            = "this";
-const char js_try_str[]             = "try";
-const char js_typeof_str[]          = "typeof";
-const char js_void_str[]            = "void";
-const char js_while_str[]           = "while";
-const char js_with_str[]            = "with";
 
 // Use a low initial capacity for atom hash tables to avoid penalizing runtimes
 // which create a small number of atoms.
diff --git a/js/src/jsatom.h b/js/src/jsatom.h
index 496dcbb4c..0a5fd3c14 100644
--- a/js/src/jsatom.h
+++ b/js/src/jsatom.h
@@ -142,44 +142,9 @@ FOR_EACH_COMMON_PROPERTYNAME(DECLARE_CONST_CHAR_STR)
 #undef DECLARE_CONST_CHAR_STR
 
 /* Constant strings that are not atomized. */
-extern const char js_break_str[];
-extern const char js_case_str[];
-extern const char js_catch_str[];
-extern const char js_class_str[];
-extern const char js_close_str[];
-extern const char js_const_str[];
-extern const char js_continue_str[];
-extern const char js_debugger_str[];
-extern const char js_default_str[];
-extern const char js_do_str[];
-extern const char js_else_str[];
-extern const char js_enum_str[];
-extern const char js_export_str[];
-extern const char js_extends_str[];
-extern const char js_finally_str[];
-extern const char js_for_str[];
 extern const char js_getter_str[];
-extern const char js_if_str[];
-extern const char js_implements_str[];
-extern const char js_import_str[];
-extern const char js_in_str[];
-extern const char js_instanceof_str[];
-extern const char js_interface_str[];
-extern const char js_package_str[];
-extern const char js_private_str[];
-extern const char js_protected_str[];
-extern const char js_public_str[];
 extern const char js_send_str[];
 extern const char js_setter_str[];
-extern const char js_static_str[];
-extern const char js_super_str[];
-extern const char js_switch_str[];
-extern const char js_this_str[];
-extern const char js_try_str[];
-extern const char js_typeof_str[];
-extern const char js_void_str[];
-extern const char js_while_str[];
-extern const char js_with_str[];
 
 namespace js {
 
diff --git a/js/src/moz.build b/js/src/moz.build
index eb30866c8..a0f074d1c 100644
--- a/js/src/moz.build
+++ b/js/src/moz.build
@@ -619,11 +619,11 @@ else:
         'perf/pm_stub.cpp'
     ]
 
-GENERATED_FILES += ['jsautokw.h']
-jsautokw = GENERATED_FILES['jsautokw.h']
-jsautokw.script = 'jsautokw.py'
-jsautokw.inputs += [
-    'vm/Keywords.h'
+GENERATED_FILES += ['frontend/ReservedWordsGenerated.h']
+ReservedWordsGenerated = GENERATED_FILES['frontend/ReservedWordsGenerated.h']
+ReservedWordsGenerated.script = 'frontend/GenerateReservedWords.py'
+ReservedWordsGenerated.inputs += [
+    'frontend/ReservedWords.h'
 ]
 
 # JavaScript must be built shared, even for static builds, as it is used by
diff --git a/js/src/vm/CommonPropertyNames.h b/js/src/vm/CommonPropertyNames.h
index eaeea84b9..8e35e1aae 100644
--- a/js/src/vm/CommonPropertyNames.h
+++ b/js/src/vm/CommonPropertyNames.h
@@ -38,6 +38,7 @@
     macro(Bool32x4, Bool32x4, "Bool32x4") \
     macro(Bool64x2, Bool64x2, "Bool64x2") \
     macro(boundWithSpace, boundWithSpace, "bound ") \
+    macro(break, break_, "break") \
     macro(breakdown, breakdown, "breakdown") \
     macro(buffer, buffer, "buffer") \
     macro(builder, builder, "builder") \
@@ -52,8 +53,10 @@
     macro(callee, callee, "callee") \
     macro(caller, caller, "caller") \
     macro(callFunction, callFunction, "callFunction") \
+    macro(case, case_, "case") \
     macro(caseFirst, caseFirst, "caseFirst") \
-    macro(class_, class_, "class") \
+    macro(catch, catch_, "catch") \
+    macro(class, class_, "class") \
     macro(close, close, "close") \
     macro(Collator, Collator, "Collator") \
     macro(CollatorCompareGet, CollatorCompareGet, "Intl_Collator_compare_get") \
@@ -62,9 +65,11 @@
     macro(comma, comma, ",") \
     macro(compare, compare, "compare") \
     macro(configurable, configurable, "configurable") \
+    macro(const, const_, "const") \
     macro(construct, construct, "construct") \
     macro(constructContentFunction, constructContentFunction, "constructContentFunction") \
     macro(constructor, constructor, "constructor") \
+    macro(continue, continue_, "continue") \
     macro(ConvertAndCopyTo, ConvertAndCopyTo, "ConvertAndCopyTo") \
     macro(copyWithin, copyWithin, "copyWithin") \
     macro(count, count, "count") \
@@ -76,28 +81,32 @@
     macro(DateTimeFormatFormatToParts, DateTimeFormatFormatToParts, "Intl_DateTimeFormat_formatToParts") \
     macro(day, day, "day") \
     macro(dayPeriod, dayPeriod, "dayPeriod") \
+    macro(debugger, debugger, "debugger") \
     macro(decodeURI, decodeURI, "decodeURI") \
     macro(decodeURIComponent, decodeURIComponent, "decodeURIComponent") \
     macro(DefaultBaseClassConstructor, DefaultBaseClassConstructor, "DefaultBaseClassConstructor") \
     macro(DefaultDerivedClassConstructor, DefaultDerivedClassConstructor, "DefaultDerivedClassConstructor") \
-    macro(default_, default_, "default") \
+    macro(default, default_, "default") \
     macro(defineGetter, defineGetter, "__defineGetter__") \
     macro(defineProperty, defineProperty, "defineProperty") \
     macro(defineSetter, defineSetter, "__defineSetter__") \
     macro(delete, delete_, "delete") \
     macro(deleteProperty, deleteProperty, "deleteProperty") \
     macro(displayURL, displayURL, "displayURL") \
+    macro(do, do_, "do") \
     macro(done, done, "done") \
     macro(dotGenerator, dotGenerator, ".generator") \
     macro(dotThis, dotThis, ".this") \
     macro(each, each, "each") \
     macro(elementType, elementType, "elementType") \
+    macro(else, else_, "else") \
     macro(empty, empty, "") \
     macro(emptyRegExp, emptyRegExp, "(?:)") \
     macro(encodeURI, encodeURI, "encodeURI") \
     macro(encodeURIComponent, encodeURIComponent, "encodeURIComponent") \
     macro(endTimestamp, endTimestamp, "endTimestamp") \
     macro(entries, entries, "entries") \
+    macro(enum, enum_, "enum") \
     macro(enumerable, enumerable, "enumerable") \
     macro(enumerate, enumerate, "enumerate") \
     macro(era, era, "era") \
@@ -105,11 +114,14 @@
     macro(escape, escape, "escape") \
     macro(eval, eval, "eval") \
     macro(exec, exec, "exec") \
+    macro(export, export_, "export") \
+    macro(extends, extends, "extends") \
     macro(false, false_, "false") \
     macro(fieldOffsets, fieldOffsets, "fieldOffsets") \
     macro(fieldTypes, fieldTypes, "fieldTypes") \
     macro(fileName, fileName, "fileName") \
     macro(fill, fill, "fill") \
+    macro(finally, finally_, "finally") \
     macro(find, find, "find") \
     macro(findIndex, findIndex, "findIndex") \
     macro(firstDayOfWeek, firstDayOfWeek, "firstDayOfWeek") \
@@ -121,6 +133,7 @@
     macro(Float32x4, Float32x4, "Float32x4") \
     macro(float64, float64, "float64") \
     macro(Float64x2, Float64x2, "Float64x2") \
+    macro(for, for_, "for") \
     macro(forceInterpreter, forceInterpreter, "forceInterpreter") \
     macro(forEach, forEach, "forEach") \
     macro(format, format, "format") \
@@ -146,8 +159,12 @@
     macro(hasOwn, hasOwn, "hasOwn") \
     macro(hasOwnProperty, hasOwnProperty, "hasOwnProperty") \
     macro(hour, hour, "hour") \
+    macro(if, if_, "if") \
     macro(ignoreCase, ignoreCase, "ignoreCase") \
     macro(ignorePunctuation, ignorePunctuation, "ignorePunctuation") \
+    macro(implements, implements, "implements") \
+    macro(import, import, "import") \
+    macro(in, in, "in") \
     macro(includes, includes, "includes") \
     macro(incumbentGlobal, incumbentGlobal, "incumbentGlobal") \
     macro(index, index, "index") \
@@ -158,12 +175,14 @@
     macro(innermost, innermost, "innermost") \
     macro(inNursery, inNursery, "inNursery") \
     macro(input, input, "input") \
+    macro(instanceof, instanceof, "instanceof") \
     macro(int8, int8, "int8") \
     macro(int16, int16, "int16") \
     macro(int32, int32, "int32") \
     macro(Int8x16, Int8x16, "Int8x16") \
     macro(Int16x8, Int16x8, "Int16x8") \
     macro(Int32x4, Int32x4, "Int32x4") \
+    macro(interface, interface, "interface") \
     macro(InterpretGeneratorResume, InterpretGeneratorResume, "InterpretGeneratorResume") \
     macro(isEntryPoint, isEntryPoint, "isEntryPoint") \
     macro(isExtensible, isExtensible, "isExtensible") \
@@ -240,13 +259,17 @@
     macro(outOfMemory, outOfMemory, "out of memory") \
     macro(ownKeys, ownKeys, "ownKeys") \
     macro(Object_valueOf, Object_valueOf, "Object_valueOf") \
+    macro(package, package, "package") \
     macro(parseFloat, parseFloat, "parseFloat") \
     macro(parseInt, parseInt, "parseInt") \
     macro(pattern, pattern, "pattern") \
     macro(pending, pending, "pending") \
+    macro(public, public_, "public") \
     macro(preventExtensions, preventExtensions, "preventExtensions") \
+    macro(private, private_, "private") \
     macro(promise, promise, "promise") \
     macro(propertyIsEnumerable, propertyIsEnumerable, "propertyIsEnumerable") \
+    macro(protected, protected_, "protected") \
     macro(proto, proto, "__proto__") \
     macro(prototype, prototype, "prototype") \
     macro(proxy, proxy, "proxy") \
@@ -295,10 +318,12 @@
     macro(StructType, StructType, "StructType") \
     macro(style, style, "style") \
     macro(super, super, "super") \
+    macro(switch, switch_, "switch") \
     macro(Symbol_iterator_fun, Symbol_iterator_fun, "[Symbol.iterator]") \
     macro(target, target, "target") \
     macro(test, test, "test") \
     macro(then, then, "then") \
+    macro(this, this_, "this") \
     macro(throw, throw_, "throw") \
     macro(timestamp, timestamp, "timestamp") \
     macro(timeZone, timeZone, "timeZone") \
@@ -311,7 +336,9 @@
     macro(toString, toString, "toString") \
     macro(toUTCString, toUTCString, "toUTCString") \
     macro(true, true_, "true") \
+    macro(try, try_, "try") \
     macro(type, type, "type") \
+    macro(typeof, typeof_, "typeof") \
     macro(uint8, uint8, "uint8") \
     macro(uint8Clamped, uint8Clamped, "uint8Clamped") \
     macro(uint16, uint16, "uint16") \
@@ -331,6 +358,7 @@
     macro(useAsm, useAsm, "use asm") \
     macro(useGrouping, useGrouping, "useGrouping") \
     macro(useStrict, useStrict, "use strict") \
+    macro(void, void_, "void") \
     macro(value, value, "value") \
     macro(valueOf, valueOf, "valueOf") \
     macro(values, values, "values") \
@@ -345,6 +373,8 @@
     macro(weekday, weekday, "weekday") \
     macro(weekendEnd, weekendEnd, "weekendEnd") \
     macro(weekendStart, weekendStart, "weekendStart") \
+    macro(while, while_, "while") \
+    macro(with, with, "with") \
     macro(writable, writable, "writable") \
     macro(year, year, "year") \
     macro(yield, yield, "yield") \
diff --git a/js/src/vm/Keywords.h b/js/src/vm/Keywords.h
deleted file mode 100644
index ef37c4419..000000000
--- a/js/src/vm/Keywords.h
+++ /dev/null
@@ -1,66 +0,0 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
- * vim: set ts=8 sts=4 et sw=4 tw=99:
- * 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/. */
-
-/* A higher-order macro for enumerating keyword tokens. */
-
-#ifndef vm_Keywords_h
-#define vm_Keywords_h
-
-#define FOR_EACH_JAVASCRIPT_KEYWORD(macro) \
-    macro(false, false_, TOK_FALSE) \
-    macro(true, true_, TOK_TRUE) \
-    macro(null, null, TOK_NULL) \
-    /* Keywords. */ \
-    macro(break, break_, TOK_BREAK) \
-    macro(case, case_, TOK_CASE) \
-    macro(catch, catch_, TOK_CATCH) \
-    macro(const, const_, TOK_CONST) \
-    macro(continue, continue_, TOK_CONTINUE) \
-    macro(debugger, debugger, TOK_DEBUGGER) \
-    macro(default, default_, TOK_DEFAULT) \
-    macro(delete, delete_, TOK_DELETE) \
-    macro(do, do_, TOK_DO) \
-    macro(else, else_, TOK_ELSE) \
-    macro(finally, finally_, TOK_FINALLY) \
-    macro(for, for_, TOK_FOR) \
-    macro(function, function, TOK_FUNCTION) \
-    macro(if, if_, TOK_IF) \
-    macro(in, in, TOK_IN) \
-    macro(instanceof, instanceof, TOK_INSTANCEOF) \
-    macro(new, new_, TOK_NEW) \
-    macro(return, return_, TOK_RETURN) \
-    macro(switch, switch_, TOK_SWITCH) \
-    macro(this, this_, TOK_THIS) \
-    macro(throw, throw_, TOK_THROW) \
-    macro(try, try_, TOK_TRY) \
-    macro(typeof, typeof, TOK_TYPEOF) \
-    macro(var, var, TOK_VAR) \
-    macro(void, void_, TOK_VOID) \
-    macro(while, while_, TOK_WHILE) \
-    macro(with, with, TOK_WITH) \
-    macro(import, import, TOK_IMPORT) \
-    macro(export, export, TOK_EXPORT) \
-    macro(class, class_, TOK_CLASS) \
-    macro(extends, extends, TOK_EXTENDS) \
-    macro(super, super, TOK_SUPER) \
-    /* Reserved keywords. */ \
-    macro(enum, enum_, TOK_RESERVED) \
-    /* Future reserved keywords, but only in strict mode. */ \
-    macro(implements, implements, TOK_STRICT_RESERVED) \
-    macro(interface, interface, TOK_STRICT_RESERVED) \
-    macro(package, package, TOK_STRICT_RESERVED) \
-    macro(private, private_, TOK_STRICT_RESERVED) \
-    macro(protected, protected_, TOK_STRICT_RESERVED) \
-    macro(public, public_, TOK_STRICT_RESERVED) \
-    macro(await, await, TOK_AWAIT) \
-    /* \
-     * Yield is a token inside function*.  Outside of a function*, it is a \
-     * future reserved keyword in strict mode, but a keyword in JS1.7 even \
-     * when strict.  Punt logic to parser. \
-     */ \
-    macro(yield, yield, TOK_YIELD)
-
-#endif /* vm_Keywords_h */
diff --git a/js/src/wasm/AsmJS.cpp b/js/src/wasm/AsmJS.cpp
index 81795b47d..51632a683 100644
--- a/js/src/wasm/AsmJS.cpp
+++ b/js/src/wasm/AsmJS.cpp
@@ -7057,7 +7057,7 @@ ParseFunction(ModuleValidator& m, ParseNode** fnOut, unsigned* line)
     TokenKind tk;
     if (!tokenStream.getToken(&tk, TokenStream::Operand))
         return false;
-    if (tk != TOK_NAME && tk != TOK_YIELD)
+    if (!TokenKindIsPossibleIdentifier(tk))
         return false;  // The regular parser will throw a SyntaxError, no need to m.fail.
 
     RootedPropertyName name(m.cx(), m.parser().bindingIdentifier(YieldIsName));
-- 
cgit v1.2.3