Completely clear the heap ages array.

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index dd68247a3e90296e58ccaac0d73b2f053e8642c1..916336b13157c7f67a498a03af7c4fdb9bc506df 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -1106,7 +1106,7 @@ void ThreadState::invokePreFinalizers(Visitor& visitor)
 
 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;
 }