Uses the activedescendant_changed event received from Blink to fire the right focus event

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

Index: third_party/WebKit/Source/modules/accessibility/AXObject.h
diff --git a/third_party/WebKit/Source/modules/accessibility/AXObject.h b/third_party/WebKit/Source/modules/accessibility/AXObject.h
index 6cc68f4bfc659ef37331554fcbf18e82c7a6385a..d21d971c15b949a9519c8a27d767f3bdf3d4ecd7 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXObject.h
+++ b/third_party/WebKit/Source/modules/accessibility/AXObject.h
@@ -744,7 +744,7 @@ public:
     virtual String stringValue() const { return String(); }
 
     // ARIA attributes.
-    virtual AXObject* activeDescendant() const { return nullptr; }
+    virtual AXObject* activeDescendant() { return nullptr; }
     virtual String ariaAutoComplete() const { return String(); }
     virtual String ariaDescribedByAttribute() const { return String(); }
     virtual void ariaFlowToElements(AXObjectVector&) const { }