Adding role 'RubyRole' in blink to expose HTML Ruby tag.

Source/core/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 123 matching lines @@
     PopUpButtonRole,
     PreRole,
     PresentationalRole,
     ProgressIndicatorRole,
     RadioButtonRole,
     RadioGroupRole,
     RegionRole,
     RootWebAreaRole,
     RowHeaderRole,
     RowRole,
+    RubyRole,
     RulerMarkerRole,
     RulerRole,
     SVGRootRole,
     ScrollAreaRole,
     ScrollBarRole,
     SeamlessWebAreaRole,
     SearchRole,
     SheetRole,
     SliderRole,
     SliderThumbRole,
@@ skipping 456 matching lines @@
     // functions called here may only search up the tree (ancestors), not down.
     void updateCachedAttributeValuesIfNeeded() const;
 };
 
 #define DEFINE_AX_OBJECT_TYPE_CASTS(thisType, predicate) \
     DEFINE_TYPE_CASTS(thisType, AXObject, object, object->predicate, object.predicate)
 
 } // namespace blink
 
 #endif // AXObject_h