Check whether aria-expanded attribute is defined

Source/core/accessibility/AXObject.h

Index: Source/core/accessibility/AXObject.h
diff --git a/Source/core/accessibility/AXObject.h b/Source/core/accessibility/AXObject.h
index cf853a6b877e6954ee4e395ebbeaeccbfe9ef805..ba2c96d709629fae8f59c908c36f70a2ed1544c5 100644
--- a/Source/core/accessibility/AXObject.h
+++ b/Source/core/accessibility/AXObject.h
@@ -194,7 +194,6 @@ enum AccessibilityTextSource {
 enum AccessibilityState {
     AXBusyState,
     AXCheckedState,
-    AXCollapsedState,
     AXEnabledState,
     AXExpandedState,
     AXFocusableState,
@@ -257,6 +256,12 @@ enum AccessibilityTextDirection {
     AccessibilityTextDirectionBottomToTop
 };
 
+enum AccessibilityExpanded {
+    ExpandedUndefined = 0,
+    ExpandedCollapsed,
+    ExpandedExpanded,
+};
+
 class AXObject : public RefCounted<AXObject> {
 public:
     typedef Vector<RefPtr<AXObject> > AccessibilityChildrenVector;
@@ -365,7 +370,7 @@ public:
     virtual bool isClickable() const;
     virtual bool isCollapsed() const { return false; }
     virtual bool isEnabled() const { return false; }
-    virtual bool isExpanded() const { return false; }
+    virtual AccessibilityExpanded isExpanded() const { return ExpandedUndefined; }
     virtual bool isFocused() const { return false; }
     virtual bool isHovered() const { return false; }
     virtual bool isIndeterminate() const { return false; }