[heap] Make the current GCCallbackFlags are part of {Heap}.

test/cctest/cctest.h

 // Copyright 2008 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 528 matching lines @@
 // marking is completed.
 static inline void SimulateIncrementalMarking(i::Heap* heap,
                                               bool force_completion = true) {
   i::MarkCompactCollector* collector = heap->mark_compact_collector();
   i::IncrementalMarking* marking = heap->incremental_marking();
   if (collector->sweeping_in_progress()) {
     collector->EnsureSweepingCompleted();
   }
   CHECK(marking->IsMarking() || marking->IsStopped());
   if (marking->IsStopped()) {
-    marking->Start(i::Heap::kNoGCFlags);
+    heap->StartIncrementalMarking();
   }
   CHECK(marking->IsMarking());
   if (!force_completion) return;
 
   while (!marking->IsComplete()) {
     marking->Step(i::MB, i::IncrementalMarking::NO_GC_VIA_STACK_GUARD);
     if (marking->IsReadyToOverApproximateWeakClosure()) {
       marking->MarkObjectGroups();
     }
   }
@@ skipping 40 matching lines @@
   HandleAndZoneScope() {}
 
   // Prefixing the below with main_ reduces a lot of naming clashes.
   i::Zone* main_zone() { return &main_zone_; }
 
  private:
   i::Zone main_zone_;
 };
 
 #endif  // ifndef CCTEST_H_