Oilpan: Implement bitmap marking

Source/platform/heap/ThreadState.cpp

 /*
  * Copyright (C) 2013 Google Inc. 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
@@ skipping 861 matching lines @@
     for (int i = 0; i < NumberOfHeaps; i++) {
         BaseHeap* heap = m_heaps[i];
         heap->makeConsistentForSweeping();
         // If a new GC is requested before this thread got around to sweep, ie. due to the
         // thread doing a long running operation, we clear the mark bits and mark any of
         // the dead objects as dead. The latter is used to ensure the next GC marking does
         // not trace already dead objects. If we trace a dead object we could end up tracing
         // into garbage or the middle of another object via the newly conservatively found
         // object.
         if (sweepRequested())
-            heap->clearLiveAndMarkDead();
+            heap->makeUnmarkedObjectsDead();
+        heap->clearObjectMarkBitMaps();
     }
     prepareRegionTree();
     setSweepRequested();
     flushHeapDoesNotContainCacheIfNeeded();
 }
 
 void ThreadState::setupHeapsForTermination()
 {
     for (int i = 0; i < NumberOfHeaps; i++)
         m_heaps[i]->prepareHeapForTermination();
@@ skipping 270 matching lines @@
             return gcInfo;
         }
     }
     if (needLockForIteration)
         threadAttachMutex().unlock();
     return 0;
 }
 #endif
 
 } // namespace blink