Add MarkRole in blink side to expose mark tag properly

Source/modules/accessibility/AXNodeObject.cpp

 /*
 * Copyright (C) 2012, Google Inc. All rights reserved.
 *
 * 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.
 * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 419 matching lines @@
 
     if (isHTMLFormElement(*node()))
         return FormRole;
 
     if (node()->hasTagName(articleTag))
         return ArticleRole;
 
     if (node()->hasTagName(mainTag))
         return MainRole;
 
+    if (node()->hasTagName(markTag))
+        return MarkRole;
+
     if (node()->hasTagName(navTag))
         return NavigationRole;
 
     if (node()->hasTagName(asideTag))
         return ComplementaryRole;
 
     if (node()->hasTagName(preTag))
         return PreRole;
 
     if (node()->hasTagName(sectionTag))
@@ skipping 1932 matching lines @@
         ariaLabeledByElements(elements);
 
         for (const auto& element : elements) {
             RefPtr<AXObject> axElement = axObjectCache()->getOrCreate(element);
             textOrder.append(AccessibilityText(ariaLabeledBy, AlternativeText, axElement));
         }
     }
 }
 
 } // namespace blink