Remove some redundant code from accessibility table headers

Source/modules/accessibility/AXTableRow.cpp

Index: Source/modules/accessibility/AXTableRow.cpp
diff --git a/Source/modules/accessibility/AXTableRow.cpp b/Source/modules/accessibility/AXTableRow.cpp
index 9fe4024a9e8af1830abf9e49511664e426e3d77b..046587a8b5070d0cbb3dd1bdc62206eb28d43464 100644
--- a/Source/modules/accessibility/AXTableRow.cpp
+++ b/Source/modules/accessibility/AXTableRow.cpp
@@ -103,27 +103,12 @@ AXObject* AXTableRow::parentTable() const
 
 AXObject* AXTableRow::headerObject()
 {
-    if (!m_renderer || !m_renderer->isTableRow())
-        return 0;
-
-    AccessibilityChildrenVector rowChildren = children();
-    if (!rowChildren.size())
-        return 0;
-
-    // check the first element in the row to see if it is a TH element
-    AXObject* cell = rowChildren[0].get();
-    if (!cell->isTableCell())
-        return 0;
-
-    LayoutObject* cellRenderer = toAXTableCell(cell)->renderer();
-    if (!cellRenderer)
-        return 0;
-
-    Node* cellNode = cellRenderer->node();
-    if (!cellNode || !cellNode->hasTagName(thTag))
+    AccessibilityChildrenVector headers;
+    headerObjectsForRow(headers);
+    if (!headers.size())
         return 0;
 
-    return cell;
+    return headers[0].get();
 }
 
 void AXTableRow::headerObjectsForRow(AccessibilityChildrenVector& headers)