Rolling back r10049 due to webkit failures.

src/heap-inl.h

 // Copyright 2011 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 237 matching lines @@
 
 
 void Heap::FinalizeExternalString(String* string) {
   ASSERT(string->IsExternalString());
   v8::String::ExternalStringResourceBase** resource_addr =
       reinterpret_cast<v8::String::ExternalStringResourceBase**>(
           reinterpret_cast<byte*>(string) +
           ExternalString::kResourceOffset -
           kHeapObjectTag);
 
+  // Clear pointer cache.
+  ExternalString::cast(string)->clear_data_cache();
+
   // Dispose of the C++ object if it has not already been disposed.
   if (*resource_addr != NULL) {
     (*resource_addr)->Dispose();
-    *resource_addr = NULL;
   }
+
+  // Clear the resource pointer in the string.
+  *resource_addr = NULL;
 }
 
 
 MaybeObject* Heap::AllocateRawMap() {
 #ifdef DEBUG
   isolate_->counters()->objs_since_last_full()->Increment();
   isolate_->counters()->objs_since_last_young()->Increment();
 #endif
   MaybeObject* result = map_space_->AllocateRaw(Map::kSize);
   if (result->IsFailure()) old_gen_exhausted_ = true;
@@ skipping 428 matching lines @@
 
 
 Heap* _inline_get_heap_() {
   return HEAP;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_INL_H_