Completely clear the heap ages array.

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 1088 matching lines @@
     for (auto& entry : m_preFinalizers) {
         if (entry.value(entry.key, visitor))
             deadObjects.append(entry.key);
     }
     // FIXME: removeAll is inefficient.  It can shrink repeatedly.
     m_preFinalizers.removeAll(deadObjects);
 }
 
 void ThreadState::clearHeapAges()
 {
-    memset(m_heapAges, 0, sizeof(int) * NumberOfHeaps);
+    memset(m_heapAges, 0, sizeof(size_t) * NumberOfHeaps);
     memset(m_likelyToBePromptlyFreed.get(), 0, sizeof(int) * likelyToBePromptlyFreedArraySize);
     m_currentHeapAges = 0;
 }
 
 int ThreadState::heapIndexOfVectorHeapLeastRecentlyExpanded(int beginHeapIndex, int endHeapIndex)
 {
     size_t minHeapAge = m_heapAges[beginHeapIndex];
     int heapIndexWithMinHeapAge = beginHeapIndex;
     for (int heapIndex = beginHeapIndex + 1; heapIndex <= endHeapIndex; heapIndex++) {
         if (m_heapAges[heapIndex] < minHeapAge) {
@@ skipping 112 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