Support for global var shortcuts in script contexts.

src/contexts.h

Index: src/contexts.h
diff --git a/src/contexts.h b/src/contexts.h
index 6412b4f0841dd8ab5b195ac13e86b374f64c9f39..1210848384347995c42f8274212d46c4079a0be6 100644
--- a/src/contexts.h
+++ b/src/contexts.h
@@ -226,6 +226,7 @@ class ScriptContextTable : public FixedArray {
     int context_index;
     int slot_index;
     VariableMode mode;
+    VariableLocation location;
     InitializationFlag init_flag;
     MaybeAssignedFlag maybe_assigned_flag;
   };
@@ -558,6 +559,9 @@ class Context: public FixedArray {
         that->global_object()->native_context()->security_token();
   }
 
+  // Initializes global variable bindings in given script context.
+  void InitializeGlobalSlots();
+
   // A native context holds a list of all functions with optimized code.
   void AddOptimizedFunction(JSFunction* function);
   void RemoveOptimizedFunction(JSFunction* function);