Add parser support for generators.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 0f85f91583b161ceab4d80d6cd81b570f144f6d9..f0319d5de85808f03f86f5bd8b309f66cabf9285 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -479,6 +479,7 @@ class Parser {
    public:
     FunctionState(Parser* parser,
                   Scope* scope,
+                  bool is_generator,
                   Isolate* isolate);
     ~FunctionState();
 
@@ -509,6 +510,8 @@ class Parser {
     void AddProperty() { expected_property_count_++; }
     int expected_property_count() { return expected_property_count_; }
 
+    bool is_generator() const { return is_generator_; }
+
     AstNodeFactory<AstConstructionVisitor>* factory() { return &factory_; }
 
    private:
@@ -523,6 +526,9 @@ class Parser {
     // Properties count estimation.
     int expected_property_count_;
 
+    // Indicates that this function is a generator.
+    bool is_generator_;
+
     // Keeps track of assignments to properties of this. Used for
     // optimizing constructors.
     bool only_simple_this_property_assignments_;
@@ -636,6 +642,7 @@ 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);
@@ -679,6 +686,7 @@ 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);
@@ -708,6 +716,8 @@ class Parser {
     return scanner().Next();
   }
 
+  bool is_generator() const { return current_function_state_->is_generator(); }
+
   bool peek_any_identifier();
 
   INLINE(void Consume(Token::Value token));