Update pad-gesture-fling test to accommodate short-circuited fling

LayoutTests/fast/events/touch/gesture/pad-gesture-fling.js

 description("Tests basic use of GestureFlingStart");
 
 var actualWheelEventsOccurred = 0;
 var cumulativeScrollX = 0;
 var cumulativeScrollY = 0;
 
-var minimumWheelEventsExpected = 40;
-var minimumScrollXExpected = "200";
-var minimumScrollYExpected = "200";
+var maximumWheelEventsExpected = 500;
+var minimumScrollXExpected = 300;
+var minimumScrollYExpected = 300;
 
 var positionX = 10;
 var positionY = 11;
 var velocityX = 10000;
 var velocityY = 10000;
 
 function recordWheelEvent(event)
 {
     if (event.clientX != 10)
       debug('FAIL: clientX != 10');
 
     if (event.clientY != 11)
       debug('FAIL: event.clientY != 11');
 
     actualWheelEventsOccurred++;
     cumulativeScrollX += event.wheelDeltaX;
     cumulativeScrollY += event.wheelDeltaY;
 
-    if (actualWheelEventsOccurred == minimumWheelEventsExpected) {
-      shouldBeGreaterThanOrEqual('cumulativeScrollX', minimumScrollXExpected);
-      shouldBeGreaterThanOrEqual('cumulativeScrollY', minimumScrollYExpected);
+    if (actualWheelEventsOccurred == maximumWheelEventsExpected
+        || (cumulativeScrollX >= minimumScrollXExpected
+            && cumulativeScrollY >= minimumScrollYExpected
+            && actualWheelEventsOccurred < maximumWheelEventsExpected)) {

[bokan, 2014/04/01 18:37:10]

I don't think you need this last condition. If actual == maximum we wouldn't
eval here because of the ||, actual > maximum shouldn't happen since we should
have finished the test.

[jdduke (slow), 2014/04/01 18:38:45]

OK I wasn't sure if |notifyDone()| forcefully terminates the test.

+      shouldBeGreaterThanOrEqual(maximumWheelEventsExpected.toString(), 'actualWheelEventsOccurred');

[bokan, 2014/04/01 18:37:10]

This seems kind of weird, why would we want a maximum? (e.g. what happens in a
few years when we're running at 120Hz and generating way more events?)

Could we maybe just ensure we get at least 2 events? Really, a fling should
involve multiple events, we don't really care about the number otherwise...

[jdduke (slow), 2014/04/01 18:38:45]

Why 2? Why not 1?  Ideally we'd just keep going until the external timeout
fires?

+      shouldBeGreaterThanOrEqual('cumulativeScrollX', minimumScrollXExpected.toString());
+      shouldBeGreaterThanOrEqual('cumulativeScrollY', minimumScrollYExpected.toString());
 
       isSuccessfullyParsed();
       if (window.testRunner)
           testRunner.notifyDone();
     }
+    event.preventDefault();
 }
 
 document.addEventListener("mousewheel", recordWheelEvent);
 
 if (window.testRunner && window.eventSender && window.eventSender.gestureFlingStart) {
     eventSender.gestureFlingStart(positionX, positionY, velocityX, velocityY);
 }
 
 if (window.testRunner)
     testRunner.waitUntilDone();