Send AXLayoutComplete even when document hasn't finished loading yet (reland)

Source/core/accessibility/AXObjectCache.h

Index: Source/core/accessibility/AXObjectCache.h
diff --git a/Source/core/accessibility/AXObjectCache.h b/Source/core/accessibility/AXObjectCache.h
index 5024525183b484ce9210903c7836a58f9685482f..17bb04f5ab4fcf5dd11bca47bbd9cba59e9e3156 100644
--- a/Source/core/accessibility/AXObjectCache.h
+++ b/Source/core/accessibility/AXObjectCache.h
@@ -132,6 +132,8 @@ public:
     // Called when scroll bars are added / removed (as the view resizes).
     void handleScrollbarUpdate(ScrollView*);
 
+    void handleLayoutComplete(RenderObject*);
+
     // Called when the scroll offset changes.
     void handleScrollPositionChanged(ScrollView*);
     void handleScrollPositionChanged(RenderObject*);