Use window.testRunner in if-clause

third_party/WebKit/LayoutTests/fullscreen/full-screen-request-removed.html

 <p>Test for <a href="https://bugs.webkit.org/show_bug.cgi?id=62320">bug 62320</a>: 
 Emit an error event when a request to enter full-screen is rejected.</p>
 <p>Tests that the document is still messaged if the element requesting full screen is removed before the event is generated.</p>
 <script src="full-screen-test.js"></script>
 <script>
 function runTest() {
     waitForEventAndEnd(document, 'webkitfullscreenchange', function() { 
             consoleWrite("FAIL - entered full screen!"); 
     });
 
     waitForEventAndEnd(document, 'webkitfullscreenerror', function() {
         consoleWrite("SUCCEED - did not enter full screen!");
     });
 
-    if (testRunner)
+    if (window.testRunner)
         testRunner.setPopupBlockingEnabled(true);
 
     var div = document.createElement('div');
     document.documentElement.appendChild(div);
     consoleWrite("Added child element.")
     div.webkitRequestFullScreen();
     document.documentElement.removeChild(div);
     consoleWrite("Removed child element.")
 }
 
 runTest();
 </script>