Update the accessibility tree when a modal dialog is opened/closed.

Source/core/accessibility/AXObjectCache.cpp

 /*
  * Copyright (C) 2008, 2009, 2010 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 632 matching lines @@
         obj->notifyIfIgnoredValueChanged();
 }
 
 void AXObjectCache::updateCacheAfterNodeIsAttached(Node* node)
 {
     // Calling get() will update the AX object if we had an AXNodeObject but now we need
     // an AXRenderObject, because it was reparented to a location outside of a canvas.
     get(node);
 }
 
+static void inertSubtreesChanged(AXObject* object)
+{
+    if (object->notifyIfIgnoredValueChanged())
+        return;
+    AXObject::AccessibilityChildrenVector children = object->children();
+    size_t count = children.size();
+    for (size_t i = 0; i < count; ++i)
+        inertSubtreesChanged(children[i].get());
+}
+
+void AXObjectCache::handleInertSubtreesChanged()
+{
+    m_computedObjectAttributeCache->clear();
+    inertSubtreesChanged(rootObject());
+}
+
 void AXObjectCache::childrenChanged(Node* node)
 {
     childrenChanged(get(node));
 }
 
 void AXObjectCache::childrenChanged(RenderObject* renderer)
 {
     childrenChanged(get(renderer));
 }
 
@@ skipping 356 matching lines @@
 }
 
 void AXObjectCache::handleScrolledToAnchor(const Node* anchorNode)
 {
     // The anchor node may not be accessible. Post the notification for the
     // first accessible object.
     postPlatformNotification(AXObject::firstAccessibleObjectFromNode(anchorNode), AXScrolledToAnchor);
 }
 
 } // namespace WebCore