Add parser support for generators.

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index 29b1fe74c6058a344f12d75e5d9407f0b86d1ae6..0c1ed2bde96d28c4e2ac8c28d7fe000ef5dde3cb 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -3594,6 +3594,7 @@ Expression* Parser::ParsePrimaryExpression(bool* ok) {
       break;
 
     case Token::IDENTIFIER:
+    case Token::YIELD:
     case Token::FUTURE_STRICT_RESERVED_WORD: {
       Handle<String> name = ParseIdentifier(CHECK_OK);
       if (fni_ != NULL) fni_->PushVariableName(name);
@@ -4662,7 +4663,8 @@ bool Parser::peek_any_identifier() {
   Token::Value next = peek();
   return next == Token::IDENTIFIER ||
          next == Token::FUTURE_RESERVED_WORD ||
-         next == Token::FUTURE_STRICT_RESERVED_WORD;
+         next == Token::FUTURE_STRICT_RESERVED_WORD ||
+         next == Token::YIELD;
 }
 
 
@@ -4737,7 +4739,10 @@ Handle<String> Parser::ParseIdentifier(bool* ok) {
   if (!top_scope_->is_classic_mode()) {
     Expect(Token::IDENTIFIER, ok);
   } else if (!Check(Token::IDENTIFIER)) {
-    Expect(Token::FUTURE_STRICT_RESERVED_WORD, ok);
+    if (Check(Token::YIELD))
+      *ok = !inside_generator();
+    else
+      Expect(Token::FUTURE_STRICT_RESERVED_WORD, ok);
   }
   if (!*ok) return Handle<String>();
   return GetSymbol(ok);
@@ -4750,8 +4755,15 @@ Handle<String> Parser::ParseIdentifierOrStrictReservedWord(
     bool* is_strict_reserved, bool* ok) {
   *is_strict_reserved = false;
   if (!Check(Token::IDENTIFIER)) {
-    Expect(Token::FUTURE_STRICT_RESERVED_WORD, ok);
-    *is_strict_reserved = true;
+    if (Check(Token::YIELD)) {
+      if (inside_generator())
+        *ok = false;
+      else
+        *is_strict_reserved = true;
+    } else {
+      Expect(Token::FUTURE_STRICT_RESERVED_WORD, ok);
+      *is_strict_reserved = true;
+    }
   }
   if (!*ok) return Handle<String>();
   return GetSymbol(ok);