[api] Do not force external GCs when only trying to synchronously process phantom callbacks

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 4947 matching lines @@
  * such operations will result in the allocation of objects.
  */
 enum GCType {
   kGCTypeScavenge = 1 << 0,
   kGCTypeMarkSweepCompact = 1 << 1,
   kGCTypeAll = kGCTypeScavenge | kGCTypeMarkSweepCompact
 };
 
 enum GCCallbackFlags {
   kNoGCCallbackFlags = 0,
-  kGCCallbackFlagCompacted = 1 << 0,
   kGCCallbackFlagConstructRetainedObjectInfos = 1 << 1,
-  kGCCallbackFlagForced = 1 << 2
+  kGCCallbackFlagForced = 1 << 2,
+  kGCCallbackFlagSynchronousPhantomCallbackProcessing = 1 << 3
 };
 
 typedef void (*GCPrologueCallback)(GCType type, GCCallbackFlags flags);
 typedef void (*GCEpilogueCallback)(GCType type, GCCallbackFlags flags);
 
 typedef void (*InterruptCallback)(Isolate* isolate, void* data);
 
 
 /**
  * Collection of V8 heap information.
@@ skipping 3336 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_