Update textinput_helper.js to support subpixel coordinates

chrome/test/data/textinput/textinput_helper.js

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 var textinput_helper = {
   retrieveElementCoordinate: function(id) {
     var ele = document.getElementById(id);
-    var coordinate = ele.offsetLeft + ',' + ele.offsetTop + ',' +
-        ele.offsetWidth + ',' + ele.offsetHeight;
+    var coordinate = Math.floor(ele.offsetLeft) + ',' +
+        Math.floor(ele.offsetTop) + ',' +
+        Math.ceil(ele.offsetWidth) + ',' +
+        Math.ceil(ele.offsetHeight);
     window.domAutomationController.send(coordinate);
   }
 };