refactor(ngScenario): remove redundant msie variable

Author: shahata

src/ngScenario/browserTrigger.js

@@ -1,12 +1,6 @@
 'use strict';
 
 (function() {
-  /**
-   * documentMode is an IE-only property
-   * http://msdn.microsoft.com/en-us/library/ie/cc196988(v=vs.85).aspx
-   */
-  var msie = document.documentMode;
-
   /**
    * Triggers a browser event. Attempts to choose the right event if one is
    * not specified.