Postpone counters triggered during GC, and use a HandleScope when calling back.

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 5089 matching lines @@
    * list.
    */
   enum UseCounterFeature {
     kUseAsm = 0,
     kBreakIterator = 1,
     kLegacyConst = 2,
     kMarkDequeOverflow = 3,
     kStoreBufferOverflow = 4,
     kSlotsBufferOverflow = 5,
     kObjectObserve = 6,
+    kForcedGC = 7,
     kUseCounterFeatureCount  // This enum value must be last.
   };
 
   typedef void (*UseCounterCallback)(Isolate* isolate,
                                      UseCounterFeature feature);
 
 
   /**
    * Creates a new isolate.  Does not change the currently entered
    * isolate.
@@ skipping 2907 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_