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

Source/core/accessibility/AXRenderObject.cpp

Index: Source/core/accessibility/AXRenderObject.cpp
diff --git a/Source/core/accessibility/AXRenderObject.cpp b/Source/core/accessibility/AXRenderObject.cpp
index 58639de6792676352a73b738ad13d6ba8cc117b5..7c66e9084818b673f34531e6f2dc84b02977fa9e 100644
--- a/Source/core/accessibility/AXRenderObject.cpp
+++ b/Source/core/accessibility/AXRenderObject.cpp
@@ -385,6 +385,9 @@ AccessibilityRole AXRenderObject::determineAccessibilityRole()
     if (isHTMLLabelElement(node))
         return LabelRole;
 
+    if (isHTMLRubyElement(node))
+        return RubyRole;
+
     if (isHTMLDivElement(node))
         return DivRole;
 
@@ -734,6 +737,9 @@ bool AXRenderObject::computeAccessibilityIsIgnored() const
     if (roleValue() == MeterRole)
         return false;
 
+    if (roleValue() == RubyRole)
+        return false;
+
     // if this element has aria attributes on it, it should not be ignored.
     if (supportsARIAAttributes())
         return false;