Implemented IAccessible2 reverse relations.

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

Index: third_party/WebKit/Source/modules/accessibility/AXObject.cpp
diff --git a/third_party/WebKit/Source/modules/accessibility/AXObject.cpp b/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
index 5beffc588679ecf5ab2b14538b84f9e3517356c6..80e2c6d195bcca6d52c47eea1a01d458bf37ebae 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
@@ -519,9 +519,7 @@ void AXObject::updateCachedAttributeValuesIfNeeded() const
     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();
 }
 
@@ -1099,7 +1097,7 @@ bool AXObject::isLiveRegion() const
     return equalIgnoringCase(liveRegion, "polite") || equalIgnoringCase(liveRegion, "assertive");
 }
 
-const AXObject* AXObject::liveRegionRoot() const
+AXObject* AXObject::liveRegionRoot() const
 {
     updateCachedAttributeValuesIfNeeded();
     return m_cachedLiveRegionRoot;