Oilpan: Move WorkerClients to the managed heap and trace its supplements.

Source/core/clipboard/DataObject.cpp

Index: Source/core/clipboard/DataObject.cpp
diff --git a/Source/core/clipboard/DataObject.cpp b/Source/core/clipboard/DataObject.cpp
index de333b676d9dad13c77f1769fc49623403304f72..e904f89d9e290fbae463d49d80b37014efd1c28e 100644
--- a/Source/core/clipboard/DataObject.cpp
+++ b/Source/core/clipboard/DataObject.cpp
@@ -67,6 +67,10 @@ PassRefPtrWillBeRawPtr<DataObject> DataObject::copy() const
     return adoptRefWillBeNoop(new DataObject(*this));
 }
 
+DataObject::~DataObject()
+{
+}
+
 size_t DataObject::length() const
 {
     return m_itemList.size();
@@ -268,9 +272,7 @@ void DataObject::internalAddFileItem(PassRefPtrWillBeRawPtr<DataObjectItem> item
 void DataObject::trace(Visitor* visitor)
 {
     visitor->trace(m_itemList);
-#if ENABLE(OILPAN)
-    HeapSupplementable<DataObject>::trace(visitor);
-#endif
+    WillBeHeapSupplementable<DataObject>::trace(visitor);
 }
 
 } // namespace WebCore