Remove early returns in fullscreen tests

LayoutTests/fullscreen/anonymous-block-merge-crash.html

 <span><object><div>PASS</div></span>
 <script src="full-screen-test.js"></script>
 <script>
-  if (Element.prototype.webkitRequestFullScreen == undefined) {
-  } else {
     var span = document.getElementsByTagName('span')[0];
 
     document.onwebkitfullscreenchange = function(event) {
       document.body.appendChild(document.createElement('div'));
       document.webkitCancelFullScreen();
       testRunner.notifyDone();
     };
 
     runWithKeyDown(function(){span.webkitRequestFullScreen()});
-  }
 </script>