Add a flag to over approximate the weak closure during GC

src/heap/gc-tracer.h

 // Copyright 2014 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.
 
 #ifndef V8_HEAP_GC_TRACER_H_
 #define V8_HEAP_GC_TRACER_H_
 
 #include "src/base/platform/platform.h"
 
 namespace v8 {
@@ skipping 90 matching lines @@
       MC_SWEEP_CODE,
       MC_SWEEP_CELL,
       MC_SWEEP_MAP,
       MC_EVACUATE_PAGES,
       MC_UPDATE_NEW_TO_NEW_POINTERS,
       MC_UPDATE_ROOT_TO_NEW_POINTERS,
       MC_UPDATE_OLD_TO_NEW_POINTERS,
       MC_UPDATE_POINTERS_TO_EVACUATED,
       MC_UPDATE_POINTERS_BETWEEN_EVACUATED,
       MC_UPDATE_MISC_POINTERS,
+      MC_INCREMENTAL_WEAKCLOSURE,
       MC_WEAKCLOSURE,
       MC_WEAKCOLLECTION_PROCESS,
       MC_WEAKCOLLECTION_CLEAR,
       MC_WEAKCOLLECTION_ABORT,
       MC_FLUSH_CODE,
       NUMBER_OF_SCOPES
     };
 
     Scope(GCTracer* tracer, ScopeId scope) : tracer_(tracer), scope_(scope) {
       start_time_ = base::OS::TimeCurrentMillis();
@@ skipping 369 matching lines @@
 
   // Counts how many tracers were started without stopping.
   int start_counter_;
 
   DISALLOW_COPY_AND_ASSIGN(GCTracer);
 };
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_GC_TRACER_H_