Oilpan: move editing objects to the heap.

Source/wtf/VectorTraits.h

Index: Source/wtf/VectorTraits.h
diff --git a/Source/wtf/VectorTraits.h b/Source/wtf/VectorTraits.h
index 7716835a1b5c0033ff7e984f846eba86ac315932..636dd062035025e69d1b0d47d7bb4b6958274bc9 100644
--- a/Source/wtf/VectorTraits.h
+++ b/Source/wtf/VectorTraits.h
@@ -108,6 +108,15 @@ namespace WTF { \
     }; \
 }
 
+#define WTF_ALLOW_INIT_WITH_MEM_FUNCTIONS(ClassName) \
+namespace WTF { \
+    template<> \
+    struct VectorTraits<ClassName> : VectorTraitsBase<ClassName> \
+    { \
+        static const bool canInitializeWithMemset = true; \
+    }; \
+}
+
 using WTF::VectorTraits;
 using WTF::SimpleClassVectorTraits;