Revert of Reduce ActiveDOMObjects from core/

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IntersectionObserverController_h
 #define IntersectionObserverController_h
 
-#include "core/dom/ActiveDOMObject.h"
 #include "core/dom/Element.h"
 #include "core/dom/IntersectionObserver.h"
 #include "platform/Timer.h"
 #include "platform/heap/Handle.h"
 #include "wtf/HashSet.h"
 
 // Design doc for IntersectionObserver implementation:
 //   https://docs.google.com/a/google.com/document/d/1hLK0eyT5_BzyNS4OkjsnoqqFQDYCbKfyBinj94OnLiQ
 
 namespace blink {
@@ skipping 23 matching lines @@
     HeapHashSet<WeakMember<IntersectionObserver>> m_trackedIntersectionObservers;
     // IntersectionObservers for which this is the execution context of the callback.
     HeapHashSet<Member<IntersectionObserver>> m_pendingIntersectionObservers;
 
     bool m_timerFiredWhileSuspended;
 };
 
 } // namespace blink
 
 #endif // IntersectionObserverController_h