Oilpan: Prepare moving AXObject to heap

Source/core/dom/Element.h

Index: Source/core/dom/Element.h
diff --git a/Source/core/dom/Element.h b/Source/core/dom/Element.h
index 6cca778a4b41dded08715ca5236b39891bb9f40f..be6572f0b81de6aa5b0a47510376e2e799a25c72 100644
--- a/Source/core/dom/Element.h
+++ b/Source/core/dom/Element.h
@@ -39,6 +39,10 @@
 #include "platform/heap/Handle.h"
 #include "public/platform/WebFocusType.h"
 
+#if ENABLE(OILPAN)
+#include "core/dom/AXObjectCache.h"
+#endif
+
 namespace blink {
 
 class ElementAnimations;
@@ -803,6 +807,10 @@ inline void Node::removedFrom(ContainerNode* insertionPoint)
         clearFlag(InDocumentFlag);
     if (isInShadowTree() && !treeScope().rootNode().isShadowRoot())
         clearFlag(IsInShadowTreeFlag);
+#if ENABLE(OILPAN)
+    if (AXObjectCache* cache = document().existingAXObjectCache())
+        cache->remove(this);
+#endif
 }
 
 inline void Element::invalidateStyleAttribute()