Make classes and structures in core/dom fast-allocated.

Source/core/dom/MutationObserverInterestGroup.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 24 matching lines @@
 #include "core/dom/MutationObserver.h"
 #include "core/dom/Node.h"
 #include "core/dom/QualifiedName.h"
 #include "platform/heap/Handle.h"
 #include "wtf/HashMap.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 class MutationObserverInterestGroup final : public NoBaseWillBeGarbageCollected<MutationObserverInterestGroup> {
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(MutationObserverInterestGroup);
 public:
     static PassOwnPtrWillBeRawPtr<MutationObserverInterestGroup> createForChildListMutation(Node& target)
     {
         if (!target.document().hasMutationObserversOfType(MutationObserver::ChildList))
             return nullptr;
 
         MutationRecordDeliveryOptions oldValueFlag = 0;
         return createIfNeeded(target, MutationObserver::ChildList, oldValueFlag);
     }
 
@@ skipping 24 matching lines @@
 
     bool hasOldValue(MutationRecordDeliveryOptions options) { return options & m_oldValueFlag; }
 
     WillBeHeapHashMap<RawPtrWillBeMember<MutationObserver>, MutationRecordDeliveryOptions> m_observers;
     MutationRecordDeliveryOptions m_oldValueFlag;
 };
 
 }
 
 #endif // MutationObserverInterestGroup_h