Remove webkitIsFullScreen everywhere except in bindings

Source/core/dom/DocumentFullscreen.cpp

Index: Source/core/dom/DocumentFullscreen.cpp
diff --git a/Source/core/dom/DocumentFullscreen.cpp b/Source/core/dom/DocumentFullscreen.cpp
index e628a4a26995a64d50b09483953c8f48901b627a..5718fb20e7f3e0c9b5764579da04726e857577bd 100644
--- a/Source/core/dom/DocumentFullscreen.cpp
+++ b/Source/core/dom/DocumentFullscreen.cpp
@@ -47,13 +47,6 @@ void DocumentFullscreen::exitFullscreen(Document& document)
     Fullscreen::from(document).exitFullscreen();
 }
 
-bool DocumentFullscreen::webkitIsFullScreen(Document& document)
-{
-    if (Fullscreen* fullscreen = Fullscreen::fromIfExists(document))
-        return fullscreen->webkitIsFullScreen();
-    return false;
-}
-
 bool DocumentFullscreen::webkitFullScreenKeyboardInputAllowed(Document& document)
 {
     if (Fullscreen* fullscreen = Fullscreen::fromIfExists(document))