Add AX role for blockquote tag

public/web/WebAXEnums.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 59 matching lines @@
 // Accessibility roles.
 // These values must match blink::AccessibilityRole values.
 // Enforced in AssertMatchingEnums.cpp.
 enum WebAXRole {
     WebAXRoleAlertDialog = 1,
     WebAXRoleAlert,
     WebAXRoleAnnotation,
     WebAXRoleApplication,
     WebAXRoleArticle,
     WebAXRoleBanner,
+    WebAXRoleBlockquote,
     WebAXRoleBrowser,
     WebAXRoleBusyIndicator,
     WebAXRoleButton,
     WebAXRoleCanvas,
     WebAXRoleCell,
     WebAXRoleCheckBoxMenuItem,
     WebAXRoleCheckBox,
     WebAXRoleColorWell,
     WebAXRoleColumnHeader,
     WebAXRoleColumn,
@@ skipping 137 matching lines @@
 enum WebAXTextDirection {
     WebAXTextDirectionLR,
     WebAXTextDirectionRL,
     WebAXTextDirectionTB,
     WebAXTextDirectionBT
 };
 
 } // namespace blink
 
 #endif