Fix support for accessible action verbs and performing the default action.

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

 /*
  * Copyright (C) 2008, 2009, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * 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.
@@ skipping 709 matching lines @@
     virtual AXObject* nextOnLine() const { return nullptr; }
     virtual AXObject* previousOnLine() const { return nullptr; }
 
     // For an inline text box.
     // The integer horizontal pixel offset of each character in the string; negative values for RTL.
     virtual void textCharacterOffsets(Vector<int>&) const { }
     // The start and end character offset of each word in the inline text box.
     virtual void wordBoundaries(Vector<AXRange>& words) const { }
 
     // Properties of interactive elements.
-    virtual String actionVerb() const;
+    String actionVerb() const;
     virtual AccessibilityButtonState checkboxOrRadioValue() const;
     virtual InvalidState getInvalidState() const { return InvalidStateUndefined; }
     // Only used when invalidState() returns InvalidStateOther.
     virtual String ariaInvalidValue() const { return String(); }
     virtual String valueDescription() const { return String(); }
     virtual float valueForRange() const { return 0.0f; }
     virtual float maxValueForRange() const { return 0.0f; }
     virtual float minValueForRange() const { return 0.0f; }
     virtual String stringValue() const { return String(); }
 
@@ skipping 208 matching lines @@
 #define DEFINE_AX_OBJECT_TYPE_CASTS(thisType, predicate) \
     DEFINE_TYPE_CASTS(thisType, AXObject, object, object->predicate, object.predicate)
 
 } // namespace blink
 
 WTF_ALLOW_INIT_WITH_MEM_FUNCTIONS(blink::IgnoredReason);
 WTF_ALLOW_INIT_WITH_MEM_FUNCTIONS(blink::NameSource);
 WTF_ALLOW_INIT_WITH_MEM_FUNCTIONS(blink::DescriptionSource);
 
 #endif // AXObject_h