CONSOLE MESSAGE: line 28: TypeError: testRunner.setViewModeMediaFeature is not a function. (In 'testRunner.setViewModeMediaFeature("windowed")', 'testRunner.setViewModeMediaFeature' is undefined) Test the MediaQueryList interface: http://dev.w3.org/csswg/cssom-view/#the-mediaquerylist-interface. Testing removeListener in different MediaQueryList objects and the callback call sequence