Add parser support for generators.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 6dcf7f129faa021e9f0d332a44c92ea3a7517aa2..f4672925cbfb2d0b76f4c35b45075e60ae18b094 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -631,6 +631,7 @@ class Parser {
 
   Expression* ParseExpression(bool accept_IN, bool* ok);
   Expression* ParseAssignmentExpression(bool accept_IN, bool* ok);
+  Expression* ParseYieldExpression(bool* ok);
   Expression* ParseConditionalExpression(bool accept_IN, bool* ok);
   Expression* ParseBinaryExpression(int prec, bool accept_IN, bool* ok);
   Expression* ParseUnaryExpression(bool* ok);
@@ -674,6 +675,7 @@ class Parser {
   ZoneList<Expression*>* ParseArguments(bool* ok);
   FunctionLiteral* ParseFunctionLiteral(Handle<String> var_name,
                                         bool name_is_reserved,
+                                        bool is_generator,
                                         int function_token_position,
                                         FunctionLiteral::Type type,
                                         bool* ok);
@@ -703,6 +705,8 @@ class Parser {
     return scanner().Next();
   }
 
+  bool inside_generator() const { return top_scope_->inside_generator(); }
+
   bool peek_any_identifier();
 
   INLINE(void Consume(Token::Value token));