Introduce isHTMLAnchorElement and toHTMLAnchorElement

Source/core/page/DragController.cpp

 /*
  * Copyright (C) 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Google Inc.
  *
  * 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 625 matching lines @@
             }
             if (dragMode == DRAG_AUTO) {
                 if ((m_dragSourceAction & DragSourceActionImage)
                     && node->hasTagName(HTMLNames::imgTag)
                     && src->settings()
                     && src->settings()->loadsImagesAutomatically()) {
                     state.m_dragType = static_cast<DragSourceAction>(state.m_dragType | DragSourceActionImage);
                     return node;
                 }
                 if ((m_dragSourceAction & DragSourceActionLink)
-                    && node->hasTagName(HTMLNames::aTag)
-                    && static_cast<HTMLAnchorElement*>(node)->isLiveLink()) {
+                    && isHTMLAnchorElement(node)
+                    && toHTMLAnchorElement(node)->isLiveLink()) {
                     state.m_dragType = static_cast<DragSourceAction>(state.m_dragType | DragSourceActionLink);
                     return node;
                 }
             }
         }
     }
 
     // We either have nothing to drag or we have a selection and we're not over a draggable element.
     return (state.m_dragType & DragSourceActionSelection) ? startNode : 0;
 }
@@ skipping 287 matching lines @@
     return false;
 #endif
 }
 
 void DragController::cleanupAfterSystemDrag()
 {
 }
 
 } // namespace WebCore