Prevent default actions for JS-generated mouse events other than click

LayoutTests/fast/forms/range/slider-transformed.html

Index: LayoutTests/fast/forms/range/slider-transformed.html
diff --git a/LayoutTests/fast/forms/range/slider-transformed.html b/LayoutTests/fast/forms/range/slider-transformed.html
index 03f6222138667b626ad39ab4851fb100546dea68..a2a151acfede40702fcc45d4e591ac0f96b1305b 100644
--- a/LayoutTests/fast/forms/range/slider-transformed.html
+++ b/LayoutTests/fast/forms/range/slider-transformed.html
@@ -16,20 +16,14 @@
   <script type="text/javascript" charset="utf-8">
     if (window.testRunner)
         testRunner.dumpAsText();
-
-    function dispatchEvent(eventType, clientX, clientY)
-    {
-      var ev = document.createEvent("MouseEvent");
-      ev.initMouseEvent(eventType, true, true, window, 1, 1, 1, clientX, clientY, false, false, false, false, 0, document);
-      var target = document.elementFromPoint(ev.clientX, ev.clientY);
-      target.dispatchEvent(ev);
-    }
     
     function test()
     {
       // For some reason the slider needs mouseup/mousedown, not just a "click"
-      dispatchEvent("mousedown", 61, 71);
-      dispatchEvent("mouseup", 61, 71);
+      eventSender.mouseMoveTo(61, 71);
+      eventSender.mouseDown(0);
+      eventSender.mouseUp(0);
+
 
       const expectedValue = 39;
       var val = document.getElementById('slider').value;