Implemented IAccessible2 reverse relations.

third_party/WebKit/Source/modules/accessibility/AXObject.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 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 501 matching lines @@
         return;
 
     m_lastModificationCount = cache.modificationCount();
     m_cachedBackgroundColor = computeBackgroundColor();
     m_cachedIsInertOrAriaHidden = computeIsInertOrAriaHidden();
     m_cachedIsDescendantOfLeafNode = (leafNodeAncestor() != 0);
     m_cachedIsDescendantOfDisabledNode = (disabledAncestor() != 0);
     m_cachedHasInheritedPresentationalRole = (inheritsPresentationalRoleFrom() != 0);
     m_cachedIsPresentationalChild = (ancestorForWhichThisIsAPresentationalChild() != 0);
     m_cachedIsIgnored = computeAccessibilityIsIgnored();
-    m_cachedLiveRegionRoot = isLiveRegion() ?
-        this :
-        (parentObjectIfExists() ? parentObjectIfExists()->liveRegionRoot() : 0);
+    m_cachedLiveRegionRoot = isLiveRegion() ? const_cast<AXObject*>(this) : (parentObjectIfExists() ? parentObjectIfExists()->liveRegionRoot() : 0);
     m_cachedAncestorExposesActiveDescendant = computeAncestorExposesActiveDescendant();
 }
 
 bool AXObject::accessibilityIsIgnoredByDefault(IgnoredReasons* ignoredReasons) const
 {
     return defaultObjectInclusion(ignoredReasons) == IgnoreObject;
 }
 
 AXObjectInclusion AXObject::accessibilityPlatformIncludesObject() const
 {
@@ skipping 557 matching lines @@
     }
     return 0;
 }
 
 bool AXObject::isLiveRegion() const
 {
     const AtomicString& liveRegion = liveRegionStatus();
     return equalIgnoringCase(liveRegion, "polite") || equalIgnoringCase(liveRegion, "assertive");
 }
 
-const AXObject* AXObject::liveRegionRoot() const
+AXObject* AXObject::liveRegionRoot() const
 {
     updateCachedAttributeValuesIfNeeded();
     return m_cachedLiveRegionRoot;
 }
 
 const AtomicString& AXObject::containerLiveRegionStatus() const
 {
     updateCachedAttributeValuesIfNeeded();
     return m_cachedLiveRegionRoot ? m_cachedLiveRegionRoot->liveRegionStatus() : nullAtom;
 }
@@ skipping 637 matching lines @@
 
 DEFINE_TRACE(AXObject)
 {
     visitor->trace(m_children);
     visitor->trace(m_parent);
     visitor->trace(m_cachedLiveRegionRoot);
     visitor->trace(m_axObjectCache);
 }
 
 } // namespace blink