Adding MeterRole in blink to support MSAA+IA2 and AX roles for meter tag in Chromium.

Source/core/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 224 matching lines @@
     if (isHTMLSelectElement(*node())) {
         HTMLSelectElement& selectElement = toHTMLSelectElement(*node());
         return selectElement.multiple() ? ListBoxRole : PopUpButtonRole;
     }
     if (isHTMLTextAreaElement(*node()))
         return TextAreaRole;
     if (headingLevel())
         return HeadingRole;
     if (isHTMLDivElement(*node()))
         return DivRole;
+    if (isHTMLMeterElement(*node()))
+        return MeterRole;
     if (isHTMLParagraphElement(*node()))
         return ParagraphRole;
     if (isHTMLLabelElement(*node()))
         return LabelRole;
     if (isHTMLDListElement(*node()))
         return DescriptionListRole;
     if (node()->isElementNode() && node()->hasTagName(figcaptionTag))
         return FigcaptionRole;
     if (node()->isElementNode() && node()->hasTagName(figureTag))
         return FigureRole;
@@ skipping 1488 matching lines @@
     float range = maxValueForRange() - minValueForRange();
     float value = valueForRange();
 
     value += range * (percentChange / 100);
     setValue(String::number(value));
 
     axObjectCache()->postNotification(node(), AXObjectCache::AXValueChanged, true);
 }
 
 } // namespace blink