Math tag is not exposed in Accessibility.

Source/modules/accessibility/AXRenderObject.cpp

 /*
 * Copyright (C) 2008 Apple 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 350 matching lines @@
 
     if (node && node->hasTagName(ddTag))
         return DescriptionListDetailRole;
 
     if (node && node->hasTagName(dlTag))
         return DescriptionListRole;
 
     if (node && node->hasTagName(dtTag))
         return DescriptionListTermRole;
 
+    if (node && (node->nodeName() == "math"))
+        return MathRole;
+
     if (node && (node->hasTagName(rpTag) || node->hasTagName(rtTag)))
         return AnnotationRole;
 
     // Table sections should be ignored.
     if (m_renderer->isTableSection())
         return IgnoredRole;
 
     if (m_renderer->isHR())
         return SplitterRole;
 
@@ skipping 348 matching lines @@
 
     if (roleValue() == FigcaptionRole)
         return false;
 
     if (roleValue() == FigureRole)
         return false;
 
     if (roleValue() == DetailsRole)
         return false;
 
+    if (roleValue() == MathRole)
+        return false;
+
     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;
 
@@ skipping 1688 matching lines @@
         if (label && label->renderer()) {
             LayoutRect labelRect = axObjectCache()->getOrCreate(label)->elementRect();
             result.unite(labelRect);
         }
     }
 
     return result;
 }
 
 } // namespace blink