Add MarkRole in blink side to expose mark tag properly

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 96 matching lines @@
     LabelRole,
     LegendRole, // No mapping to ARIA role
     LinkRole,
     ListBoxOptionRole,
     ListBoxRole,
     ListItemRole,
     ListMarkerRole, // No mapping to ARIA role
     ListRole,
     LogRole,
     MainRole,
+    MarkRole, // No mapping to ARIA role
     MarqueeRole,
     MathRole,
     MenuBarRole,
     MenuButtonRole,
     MenuItemRole,
     MenuItemCheckBoxRole,
     MenuItemRadioRole,
     MenuListOptionRole,
     MenuListPopupRole,
     MenuRole,
@@ skipping 667 matching lines @@
     static bool includesARIAWidgetRole(const String&);
     static bool hasInteractiveARIAAttribute(const Element&);
 };
 
 #define DEFINE_AX_OBJECT_TYPE_CASTS(thisType, predicate) \
     DEFINE_TYPE_CASTS(thisType, AXObject, object, object->predicate, object.predicate)
 
 } // namespace blink
 
 #endif // AXObject_h