Invalidate cross-thread persistents on heap termination.

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 223 matching lines @@
         // Finish sweeping.
         completeSweep();
 
         // From here on ignore all conservatively discovered
         // pointers into the heap owned by this thread.
         m_isTerminating = true;
 
         // Set the terminate flag on all heap pages of this thread. This is used to
         // ensure we don't trace pages on other threads that are not part of the
         // thread local GC.
         prepareHeapForTermination();

[haraken, 2015/08/03 00:45:25]

Nit: I'd rename this to prepareForThreadStateTermination().

[sof, 2015/08/03 08:30:04]

Done.

 
+        ThreadState::crossThreadPersistentRegion().prepareForThreadStateTermination(this);
+
         // Do thread local GC's as long as the count of thread local Persistents
         // changes and is above zero.
         int oldCount = -1;
         int currentCount = persistentRegion()->numberOfPersistents();
         ASSERT(currentCount >= 0);
         while (currentCount != oldCount) {
             Heap::collectGarbageForTerminatingThread(this);
             oldCount = currentCount;
             currentCount = persistentRegion()->numberOfPersistents();
         }
@@ skipping 1273 matching lines @@
         json->beginArray(it->key.ascii().data());
         for (size_t age = 0; age <= maxHeapObjectAge; ++age)
             json->pushInteger(it->value.ages[age]);
         json->endArray();
     }
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(TRACE_DISABLED_BY_DEFAULT("blink_gc"), statsName, this, json.release());
 }
 #endif
 
 } // namespace blink