Introduce isHTMLLabelElement and toHTMLLabelElement

Source/core/accessibility/AccessibilityRenderObject.cpp

Index: Source/core/accessibility/AccessibilityRenderObject.cpp
diff --git a/Source/core/accessibility/AccessibilityRenderObject.cpp b/Source/core/accessibility/AccessibilityRenderObject.cpp
index bd9806d5bb3d2431cba9b7f380fbe714393c7555..2b8b25120e7ac98ada150d0b93ebfdf9262f1a8d 100644
--- a/Source/core/accessibility/AccessibilityRenderObject.cpp
+++ b/Source/core/accessibility/AccessibilityRenderObject.cpp
@@ -270,8 +270,8 @@ HTMLLabelElement* AccessibilityRenderObject::labelElementContainer() const
 
     // find if this has a parent that is a label
     for (Node* parentNode = m_renderer->node(); parentNode; parentNode = parentNode->parentNode()) {
-        if (parentNode->hasTagName(labelTag))
-            return static_cast<HTMLLabelElement*>(parentNode);
+        if (isHTMLLabelElement(parentNode))
+            return toHTMLLabelElement(parentNode);
     }
 
     return 0;
@@ -404,7 +404,7 @@ AccessibilityRole AccessibilityRenderObject::determineAccessibilityRole()
     if (node && node->hasTagName(pTag))
         return ParagraphRole;
 
-    if (node && node->hasTagName(labelTag))
+    if (node && isHTMLLabelElement(node))
         return LabelRole;
 
     if (node && node->hasTagName(divTag))
@@ -725,7 +725,7 @@ bool AccessibilityRenderObject::computeAccessibilityIsIgnored() const
 
     // don't ignore labels, because they serve as TitleUIElements
     Node* node = m_renderer->node();
-    if (node && node->hasTagName(labelTag))
+    if (node && isHTMLLabelElement(node))
         return false;
 
     // Anything that is content editable should not be ignored.