Add parser support for generators.

src/scopes.h

Index: src/scopes.h
diff --git a/src/scopes.h b/src/scopes.h
index 3ca2dcf0ce259c6fafc57bb05a3e4bbf2160671e..2688cfa6c9976710b1d251b4707dee6bd4efeb98 100644
--- a/src/scopes.h
+++ b/src/scopes.h
@@ -308,6 +308,10 @@ class Scope: public ZoneObject {
   // Does this scope contain a with statement.
   bool contains_with() const { return scope_contains_with_; }
 
+  // If this scope is in a function that is a generator.
+  bool inside_generator() const { return scope_inside_generator_; }
+  void set_inside_generator(bool inside) { scope_inside_generator_ = inside; }
+
   // ---------------------------------------------------------------------------
   // Accessors.
 
@@ -481,6 +485,8 @@ class Scope: public ZoneObject {
   bool scope_inside_with_;
   // This scope contains a 'with' statement.
   bool scope_contains_with_;
+  // This scope is in a function that is a generator.
+  bool scope_inside_generator_;
   // This scope or a nested catch scope or with scope contain an 'eval' call. At
   // the 'eval' call site this scope is the declaration scope.
   bool scope_calls_eval_;