Make EventHandler::ActiveIntervalTimer mockable.

LayoutTests/fast/events/touch/gesture/gesture-tap-hover-clear.html

Index: LayoutTests/fast/events/touch/gesture/gesture-tap-hover-clear.html
diff --git a/LayoutTests/fast/events/touch/gesture/gesture-tap-hover-clear.html b/LayoutTests/fast/events/touch/gesture/gesture-tap-hover-clear.html
index dd3ef9c60e9dbda45c447004b739f9bab37db69d..5523f53cd21bd6fd7dbe140f6db0988671193aa5 100644
--- a/LayoutTests/fast/events/touch/gesture/gesture-tap-hover-clear.html
+++ b/LayoutTests/fast/events/touch/gesture/gesture-tap-hover-clear.html
@@ -60,6 +60,13 @@ function runTests()
         return;
     }
 
+    if (!internals.fireActiveIntervalTimer) {
+        debug('Mocked timers are not supported by this platform');
+        return;
+    }
+
+    internals.setActiveIntervalTimerInManualMode(document, true);
+
     debug("The Don't Click Me div should not be visible.");
     shouldBe("dontClickMe.offsetTop", "0");
 
@@ -71,15 +78,7 @@ function runTests()
     debug("The Don't Click Me div should not be visible after a GestureTap on the Click Me div.");
     shouldBe(document.elementFromPoint(250, 250).id, "clickme");
     eventSender.gestureTap(250, 250);
-    waitUntilActiveCleared();
-}
-
-function waitUntilActiveCleared()
-{
-    if (dontClickMe.offsetTop != 0) {
-        return setTimeout(waitUntilActiveCleared, 10);
-    }
-
+    internals.fireActiveIntervalTimer(document);
     shouldBe("dontClickMe.offsetTop", "0");
 
     debug("The Don't Click Me div should be visible after a GestureShowPress on the Hover Over Me div.");
@@ -90,13 +89,6 @@ function waitUntilActiveCleared()
     debug("The Don't Click Me div should not be visible after a mouse move to below the Click Me div.");
     eventSender.mouseMoveTo(350, 350);
     shouldBe("dontClickMe.offsetTop", "0");
-
-    finishJSTest();
-}
-
-if (window.testRunner) {
-    window.jsTestIsAsync = true;
-    testRunner.waitUntilDone();
 }
 
 runTests();