Always adjust amount of external memory when change is reported.

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 7291 matching lines @@
                                  I::kAmountOfExternalAllocatedMemoryOffset);
   int64_t* amount_of_external_allocated_memory_at_last_global_gc =
       reinterpret_cast<int64_t*>(
           reinterpret_cast<uint8_t*>(this) +
           I::kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset);
   int64_t amount = *amount_of_external_allocated_memory + change_in_bytes;
   if (change_in_bytes > 0 &&
       amount - *amount_of_external_allocated_memory_at_last_global_gc >
           I::kExternalAllocationLimit) {
     CollectAllGarbage("external memory allocation limit reached.");
-  } else {
-    *amount_of_external_allocated_memory = amount;
   }
+  *amount_of_external_allocated_memory = amount;
   return *amount_of_external_allocated_memory;
 }
 
 
 template<typename T>
 void Isolate::SetObjectGroupId(const Persistent<T>& object,
                                UniqueId id) {
   TYPE_CHECK(Value, T);
   SetObjectGroupId(reinterpret_cast<v8::internal::Object**>(object.val_), id);
 }
@@ skipping 168 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_