fix(util): webdriver could deadlock

when prepare scripts containing promises are wrapped in a flow.execute

lib/util.js

@@ -1,7 +1,6 @@
 var q = require('q'),
-    path = require('path'),
-    webdriver = require('selenium-webdriver');
-
+    path = require('path');
+
 var STACK_SUBSTRINGS_TO_FILTER = [
   'node_modules/minijasminenode/lib/',
   'node_modules/selenium-webdriver',
@@ -52,9 +51,7 @@ exports.runFilenameOrFn_ = function(configDir, filenameOrFn, args) {
       filenameOrFn = require(path.resolve(configDir, filenameOrFn));
     }
     if (typeof filenameOrFn === 'function') {
-      var results = webdriver.promise.controlFlow().execute(function() {
-        return filenameOrFn.apply(null, args);
-      }, 'executing onPrepare').then(null, function(err) {
+      var results = q.when(filenameOrFn.apply(null, args), null, function(err) {
         err.stack = exports.filterStackTrace(err.stack);
         throw err;
       });