Introduce isHTMLAreaElement and toHTMLAreaElement

Source/core/html/HTMLMapElement.cpp

Index: Source/core/html/HTMLMapElement.cpp
diff --git a/Source/core/html/HTMLMapElement.cpp b/Source/core/html/HTMLMapElement.cpp
index c7e800c3eae7fcaeda8298ffb0dde33f5b27787c..7c6ea39fd315d41757af242cf060e104121126e4 100644
--- a/Source/core/html/HTMLMapElement.cpp
+++ b/Source/core/html/HTMLMapElement.cpp
@@ -62,8 +62,8 @@ bool HTMLMapElement::mapMouseEvent(LayoutPoint location, const LayoutSize& size,
     HTMLAreaElement* defaultArea = 0;
     Element* element = this;
     while ((element = ElementTraversal::next(element, this))) {
-        if (element->hasTagName(areaTag)) {
-            HTMLAreaElement* areaElt = static_cast<HTMLAreaElement*>(element);
+        if (isHTMLAreaElement(element)) {
+            HTMLAreaElement* areaElt = toHTMLAreaElement(element);
             if (areaElt->isDefault()) {
                 if (!defaultArea)
                     defaultArea = areaElt;
@@ -71,7 +71,7 @@ bool HTMLMapElement::mapMouseEvent(LayoutPoint location, const LayoutSize& size,
                 return true;
         }
     }
-    
+
     if (defaultArea) {
         result.setInnerNode(defaultArea);
         result.setURLElement(defaultArea);