Fix KeyedAccessStoreMode on Windows

src/ast.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1793 matching lines @@
         store_mode_(STANDARD_STORE),
         expression_(expr),
         pos_(pos),
         assignment_id_(GetNextId(isolate)),
         count_id_(GetNextId(isolate)) {}
 
  private:
   Token::Value op_;
   bool is_prefix_ : 1;
   bool is_monomorphic_ : 1;
-  KeyedAccessStoreMode store_mode_: 4;
+  KeyedAccessStoreMode store_mode_ : 5;  // Windows treats as signed,
+                                         // must have extra bit.  
   Expression* expression_;
   int pos_;
   const BailoutId assignment_id_;
   const TypeFeedbackId count_id_;
   SmallMapList receiver_types_;
 };
 
 
 class CompareOperation: public Expression {
  public:
@@ skipping 121 matching lines @@
 
  private:
   Token::Value op_;
   Expression* target_;
   Expression* value_;
   int pos_;
   BinaryOperation* binary_operation_;
   const BailoutId assignment_id_;
 
   bool is_monomorphic_ : 1;
-  KeyedAccessStoreMode store_mode_ : 4;
+  KeyedAccessStoreMode store_mode_ : 5;  // Windows treats as signed,
+                                         // must have extra bit.
   SmallMapList receiver_types_;
 };
 
 
 class Yield: public Expression {
  public:
   DECLARE_NODE_TYPE(Yield)
 
   Expression* expression() const { return expression_; }
   bool is_delegating_yield() const { return is_delegating_yield_; }
@@ skipping 1047 matching lines @@
  private:
   Isolate* isolate_;
   Zone* zone_;
   Visitor visitor_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_