Add console warning for canceling uncancelable TouchEvent

LayoutTests/fast/events/touch/touch-event-cancelable.html

 <script src="../../../resources/js-test.js"></script> 
 
 <p id="description"></p>
 <div id="console"></div>
 <script type="text/javascript">
 description('Test that touch events may or may not be marked cancelable. http://crbug.com/365681');
 
 var gotTouchMove = false;
 var touchEvent;
 
 document.addEventListener('touchmove', function(event) {
     shouldBeFalse('gotTouchMove');
     gotTouchMove = true;
     touchEvent = event;
     shouldBeFalse('touchEvent.defaultPrevented');
+    console.log('Calling preventDefault on TouchEvent with cancelable=' + event.cancelable);
     touchEvent.preventDefault();
 }, false);
 
 if (window.eventSender) {
     eventSender.addTouchPoint(152, 152);
     eventSender.touchStart();
 
     eventSender.updateTouchPoint(0, 155, 155);
     eventSender.setTouchCancelable(true);
     debug('Sending cancelable touchmove');
     eventSender.touchMove();
     shouldBeTrue('gotTouchMove');
     shouldBeTrue('touchEvent.cancelable');
     shouldBeTrue('touchEvent.defaultPrevented');
     gotTouchMove = false;
 
     debug('');
     debug('Sending uncancelable touchmove');
     eventSender.setTouchCancelable(false);
     eventSender.updateTouchPoint(0, 160, 160);
     eventSender.touchMove();
     shouldBeTrue('gotTouchMove');
     shouldBeFalse('touchEvent.cancelable');
     shouldBeFalse('touchEvent.defaultPrevented');
 } else {
    debug('This test requires --dump-render-tree.');
 }
 
 </script>