Oilpan: move WorkerGlobalScope to oilpan's heap.

Source/heap/Heap.h

Index: Source/heap/Heap.h
diff --git a/Source/heap/Heap.h b/Source/heap/Heap.h
index e970e62b0c80b1f165a749d4ecaab3bb9f18cd1b..a4a83205f0f8deb986deee177075657add0c3084 100644
--- a/Source/heap/Heap.h
+++ b/Source/heap/Heap.h
@@ -1341,6 +1341,13 @@ struct ThreadingTrait<HashMap<Key, Value, HeapAllocator, T, U, V> > {
         && (ThreadingTrait<Value>::Affinity == MainThreadOnly) ? MainThreadOnly : AnyThread;
 };
 
+template<typename First, typename Second>
+struct ThreadingTrait<WTF::KeyValuePair<First, Second> > {
+    static const ThreadAffinity Affinity =
+        (ThreadingTrait<First>::Affinity == MainThreadOnly)
+        && (ThreadingTrait<Second>::Affinity == MainThreadOnly) ? MainThreadOnly : AnyThread;
+};
+
 template<typename T, typename U, typename V>
 struct ThreadingTrait<HashSet<T, HeapAllocator, U, V> > {
     static const ThreadAffinity Affinity = ThreadingTrait<T>::Affinity;