Implement Object.getOwnPropertyDescriptor for proxies.

src/property.h

 // Copyright 2006-2008 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 188 matching lines @@
     lookup_type_ = DICTIONARY_TYPE;
     holder_ = holder;
     details_ = holder->property_dictionary()->DetailsAt(entry);
     number_ = entry;
   }
 
   void HandlerResult() {
     lookup_type_ = HANDLER_TYPE;
     holder_ = NULL;
     details_ = PropertyDetails(NONE, HANDLER);
+    cacheable_ = false;
   }
 
   void InterceptorResult(JSObject* holder) {
     lookup_type_ = INTERCEPTOR_TYPE;
     holder_ = holder;
     details_ = PropertyDetails(NONE, INTERCEPTOR);
   }
 
   void NotFound() {
     lookup_type_ = NOT_FOUND;
@@ skipping 137 matching lines @@
   JSObject* holder_;
   int number_;
   bool cacheable_;
   PropertyDetails details_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_H_