add interceptors which do not mask existing properties

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 4168 matching lines @@
    */
   bool HasInstance(Handle<Value> object);
 
  private:
   FunctionTemplate();
   friend class Context;
   friend class ObjectTemplate;
 };
 
 
-enum class PropertyHandlerFlags { kNone = 0, kAllCanRead = 1 };
+enum class PropertyHandlerFlags {
+  kNone = 0,
+  // See ALL_CAN_READ above.
+  kAllCanRead = 1,
+  // Will not call into interceptor for properties on the receiver or prototype
+  // chain.  Currently only valid for named interceptors.
+  kNonMasking = 1 << 1,
+  // Will not call into interceptor for symbol lookup.  Only meaningful for
+  // named interceptors.
+  kOnlyInterceptStrings = 1 << 2,
+};
 
 
 struct NamedPropertyHandlerConfiguration {
   NamedPropertyHandlerConfiguration(
       /** Note: getter is required **/
       GenericNamedPropertyGetterCallback getter = 0,
       GenericNamedPropertySetterCallback setter = 0,
       GenericNamedPropertyQueryCallback query = 0,
       GenericNamedPropertyDeleterCallback deleter = 0,
       GenericNamedPropertyEnumeratorCallback enumerator = 0,
@@ skipping 3716 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_