Oilpan:Allow custom handling of classes that contain weak pointers that are embedded in collections.

Source/wtf/VectorTraits.h

Index: Source/wtf/VectorTraits.h
diff --git a/Source/wtf/VectorTraits.h b/Source/wtf/VectorTraits.h
index 636dd062035025e69d1b0d47d7bb4b6958274bc9..2b6544ce35239b8d755ebc3a534c09f5d994d73e 100644
--- a/Source/wtf/VectorTraits.h
+++ b/Source/wtf/VectorTraits.h
@@ -45,7 +45,7 @@ namespace WTF {
         struct NeedsTracingLazily {
             static const bool value = NeedsTracing<T>::value;
         };
-        static const bool isWeak = IsWeak<T>::value;
+        static const WeakHandlingFlag weakHandlingFlag = NoWeakHandlingInCollections; // We don't support weak handling in vectors.
     };
 
     template<typename T>
@@ -87,7 +87,7 @@ namespace WTF {
         struct NeedsTracingLazily {
             static const bool value = ShouldBeTraced<FirstTraits>::value || ShouldBeTraced<SecondTraits>::value;
         };
-        static const bool isWeak = FirstTraits::isWeak || SecondTraits::isWeak;
+        static const WeakHandlingFlag weakHandlingFlag = NoWeakHandlingInCollections; // We don't support weak handling in vectors.
     };
 
 } // namespace WTF