Oilpan: prefer eager finalization over prefinalizers.

Source/core/dom/MutationObserver.h

Index: Source/core/dom/MutationObserver.h
diff --git a/Source/core/dom/MutationObserver.h b/Source/core/dom/MutationObserver.h
index 157ce4ca869985ad9e0abf3d62bccfdc183425aa..c38d34acca700210c2660910c58e88164bd4da54 100644
--- a/Source/core/dom/MutationObserver.h
+++ b/Source/core/dom/MutationObserver.h
@@ -60,7 +60,6 @@ using MutationRecordVector = WillBeHeapVector<RefPtrWillBeMember<MutationRecord>
 
 class MutationObserver final : public RefCountedWillBeGarbageCollectedFinalized<MutationObserver>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
-    WILL_BE_USING_PRE_FINALIZER(MutationObserver, dispose);
 public:
     enum MutationType {
         ChildList = 1 << 0,
@@ -96,6 +95,7 @@ public:
 
     WillBeHeapHashSet<RawPtrWillBeMember<Node>> getObservedNodes() const;
 
+    EAGERLY_FINALIZE();

[haraken, 2015/06/04 01:02:31]

Add a comment on why we want to eagerly finalize?

[sof, 2015/06/04 07:54:39]

Added. (I couldn't come up with anything meaningful to say without recounting
the destructor code, which is why I initially left it out.)

     DECLARE_TRACE();
 
 private:
@@ -105,8 +105,6 @@ private:
     void deliver();
     bool shouldBeSuspended() const;
 
-    void dispose();
-
     OwnPtrWillBeMember<MutationCallback> m_callback;
     MutationRecordVector m_records;
     MutationObserverRegistrationSet m_registrations;