Clarify fullscreenElement vs. currentFullScreenElement distinction

third_party/WebKit/Source/core/dom/DocumentFullscreen.cpp

 /*
  * Copyright (C) 2013, Google 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 18 matching lines @@
 
 namespace blink {
 
 bool DocumentFullscreen::fullscreenEnabled(Document& document)
 {
     return Fullscreen::fullscreenEnabled(document);
 }
 
 Element* DocumentFullscreen::fullscreenElement(Document& document)
 {
-    if (Fullscreen* fullscreen = Fullscreen::fromIfExists(document))
-        return fullscreen->fullscreenElement();
-    return 0;
+    return Fullscreen::fullscreenElementFrom(document);
 }
 
 void DocumentFullscreen::exitFullscreen(Document& document)
 {
     Fullscreen::from(document).exitFullscreen();
 }
 
-Element* DocumentFullscreen::webkitCurrentFullScreenElement(Document& document)
+Element* DocumentFullscreen::currentFullScreenElement(Document& document)
 {
-    if (Fullscreen* fullscreen = Fullscreen::fromIfExists(document))
-        return fullscreen->webkitCurrentFullScreenElement();
-    return 0;
+    return Fullscreen::currentFullScreenElementFrom(document);
 }
 
 } // namespace blink