Oilpan: Fix ASan instrumentation around heap object headers.

Source/platform/heap/Heap.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 394 matching lines @@
             ThreadState::resumeThreads();
         }
     }
 
 private:
     ThreadState* m_state;
     ThreadState::SafePointScope m_safePointScope;
     bool m_parkedAllThreads; // False if we fail to park all threads
 };
 
+NO_SANITIZE_ADDRESS
 bool HeapObjectHeader::isMarked() const
 {
     checkHeader();
-    // We need to unpoison/poison the header on ASAN since
-    // acquireLoad doesn't have the NO_SANITIZE_ADDRESS flag.
-    ASAN_UNPOISON_MEMORY_REGION(this, sizeof(this));
-    unsigned size = acquireLoad(&m_size);
-    ASAN_POISON_MEMORY_REGION(this, sizeof(this));
+    unsigned size = asanAcquireLoad(&m_size);
     return size & markBitMask;
 }
 
 NO_SANITIZE_ADDRESS
 void HeapObjectHeader::unmark()
 {
     checkHeader();
     m_size &= ~markBitMask;
 }
 
@@ skipping 2413 matching lines @@
 CallbackStack* Heap::s_markingStack;
 CallbackStack* Heap::s_postMarkingCallbackStack;
 CallbackStack* Heap::s_weakCallbackStack;
 CallbackStack* Heap::s_ephemeronStack;
 HeapDoesNotContainCache* Heap::s_heapDoesNotContainCache;
 bool Heap::s_shutdownCalled = false;
 bool Heap::s_lastGCWasConservative = false;
 FreePagePool* Heap::s_freePagePool;
 OrphanedPagePool* Heap::s_orphanedPagePool;
 }