Fix run_ppapi_ppp_input_event_browser_test and re-enable it.

ppapi/native_client/tests/ppapi_browser/ppp_input_event/ppapi_ppp_input_event.js

 // Copyright (c) 2011 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.
 
 function setupTests(tester, plugin) {
   //////////////////////////////////////////////////////////////////////////////
   // Test Helpers
   //////////////////////////////////////////////////////////////////////////////
 
   // These are the coordinates of the upper-left corner of the nacl plugin
-  // TODO(mball): Avoid hardcoding this location by querying the location
-  // of the plugin.
-  var leftCorner = 8, topCorner = 79
+  var leftCorner = plugin.offsetLeft;
+  var topCorner = plugin.offsetTop;
 
   function simulateMouseEvent(eventName) {
     var event = document.createEvent('MouseEvents');
     event.initMouseEvent(
         eventName,
         true,                      // bubbles
         true,                       // cancelable
         document.defaultView,
         1,                          // one click
         0, 0,                       // Screen coordinate
@@ skipping 56 matching lines @@
     addTest(
       testName,
       'mousedown',
       'PP_INPUTEVENT_TYPE_MOUSEDOWN' +
           ':PP_INPUTEVENT_MODIFIER_LEFTBUTTONDOWN' +
           ':PP_INPUTEVENT_MOUSEBUTTON_LEFT' +
           ':Position=0,0:ClickCount=1',
       simulateMouseEvent);
   });
 }