Revert of Oilpan: Fix weak processing for IntersectionObserver::m_root

third_party/WebKit/Source/core/dom/IntersectionObserver.h

Index: third_party/WebKit/Source/core/dom/IntersectionObserver.h
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObserver.h b/third_party/WebKit/Source/core/dom/IntersectionObserver.h
index d3e61cd97644ebe1699f86c580266681ddbeb988..a918acb4cab2f8f6a182a4fbfbeecd9ebbc6672f 100644
--- a/third_party/WebKit/Source/core/dom/IntersectionObserver.h
+++ b/third_party/WebKit/Source/core/dom/IntersectionObserver.h
@@ -27,6 +27,7 @@
 public:
     static IntersectionObserver* create(const IntersectionObserverInit&, IntersectionObserverCallback&, ExceptionState&);
     static void resumeSuspendedObservers();
+    static void rootDisappearedCallback(Visitor*, void*);
 
     // API methods
     void observe(Element*, ExceptionState&);
@@ -55,9 +56,6 @@
 
 private:
     explicit IntersectionObserver(IntersectionObserverCallback&, Node&, const Vector<Length>& rootMargin, const Vector<float>& thresholds);
-#if ENABLE(OILPAN)
-    void clearWeakMembers(Visitor*);
-#endif
 
     Member<IntersectionObserverCallback> m_callback;
     WeakPtrWillBeWeakMember<Node> m_root;