Adding isTableHeaderCell method.

Source/modules/accessibility/AXTableCell.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 33 matching lines @@
 
 AXTableCell::~AXTableCell()
 {
 }
 
 PassRefPtr<AXTableCell> AXTableCell::create(RenderObject* renderer, AXObjectCacheImpl* axObjectCache)
 {
     return adoptRef(new AXTableCell(renderer, axObjectCache));
 }
 
+bool AXTableCell::isTableHeaderCell() const
+{
+    return node() && node()->hasTagName(thTag);
+}
+
 bool AXTableCell::computeAccessibilityIsIgnored() const
 {
     AXObjectInclusion decision = defaultObjectInclusion();
     if (decision == IncludeObject)
         return false;
     if (decision == IgnoreObject)
         return true;
 
     if (!isTableCell())
         return AXRenderObject::computeAccessibilityIsIgnored();
@@ skipping 33 matching lines @@
         return CellRole;
     if (siblingNode->hasTagName(thTag))
         return ColumnHeaderRole;
     if (siblingNode->hasTagName(tdTag))
         return RowHeaderRole;
     return CellRole;
 }
 
 AccessibilityRole AXTableCell::scanToDecideHeaderRole()
 {
-    Node* node = m_renderer ? m_renderer->node() : 0;
-    if (!node || !node->hasTagName(thTag))
+    if (!isTableHeaderCell())
         return CellRole;
 
     // Check scope attribute first.
     const AtomicString& scope = getAttribute(scopeAttr);
     if (equalIgnoringCase(scope, "row"))
         return RowHeaderRole;
     if (equalIgnoringCase(scope, "col"))
         return ColumnHeaderRole;
 
     // Check the previous cell and the next cell
@@ skipping 94 matching lines @@
         return 0;
 
     Node* cellElement = headerCell->node();
     if (!cellElement || !cellElement->hasTagName(thTag))
         return 0;
 
     return axObjectCache()->getOrCreate(headerCell);
 }
 
 } // namespace blink