Oilpan: Support polymorphic objects in HeapVectorBackings

Source/wtf/Vector.h

Index: Source/wtf/Vector.h
diff --git a/Source/wtf/Vector.h b/Source/wtf/Vector.h
index 6a52675cb750dba0308bb88990634058930791e2..967a50eae71c945915f1017a89ec32854c9b9a9d 100644
--- a/Source/wtf/Vector.h
+++ b/Source/wtf/Vector.h
@@ -90,7 +90,7 @@ static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
     struct VectorUnusedSlotClearer<true, T> {
         static void clear(T* begin, T* end)
         {
-            memset(begin, 0, sizeof(T) * (end - begin));
+            memset(reinterpret_cast<void*>(begin), 0, sizeof(T) * (end - begin));

[tkent, 2015/05/07 00:43:21]

Why do you do reinterpret_cast<>?

[haraken, 2015/05/07 00:49:40]

Because without the reinterpret_cast, clang complains that we should not use
memset for slots that contain vtables. We use this technique to avoid the
compile error in some places in platform/heap/.

[tkent, 2015/05/08 06:42:00]

Thanks.  lgtm

         }
 
 #if ENABLE(ASSERT)