Oilpan: Prepare to move AXObjectCache to the heap

Source/modules/accessibility/AXObjectCacheImpl.h

Index: Source/modules/accessibility/AXObjectCacheImpl.h
diff --git a/Source/modules/accessibility/AXObjectCacheImpl.h b/Source/modules/accessibility/AXObjectCacheImpl.h
index acff085d22a73ffc4ef977d868ba7a43d8eb3210..a40172d3bdd1de069a4005cc40b382fff58e5004 100644
--- a/Source/modules/accessibility/AXObjectCacheImpl.h
+++ b/Source/modules/accessibility/AXObjectCacheImpl.h
@@ -55,15 +55,18 @@ struct TextMarkerData {
 
 // This class should only be used from inside the accessibility directory.
 class MODULES_EXPORT AXObjectCacheImpl : public AXObjectCache {
-    WTF_MAKE_NONCOPYABLE(AXObjectCacheImpl); WTF_MAKE_FAST_ALLOCATED(AXObjectCacheImpl);
+    WTF_MAKE_NONCOPYABLE(AXObjectCacheImpl);
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(AXObjectCacheImpl);
 public:
-    static PassOwnPtr<AXObjectCache> create(Document&);
+    static PassOwnPtrWillBeRawPtr<AXObjectCache> create(Document&);
 
     explicit AXObjectCacheImpl(Document&);
     ~AXObjectCacheImpl();
 
     AXObject* focusedUIElementForPage(const Page*);
 
+    virtual void dispose() override;
+
     virtual void selectionChanged(Node*) override;
     virtual void childrenChanged(Node*) override;
     virtual void childrenChanged(LayoutObject*) override;