MD Downloads: fix vulcanize issues by excluding higher up in the dependency tree

chrome/test/data/webui/polymer_browser_test_base.js

 // Copyright 2015 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.
 
 /**
  * @fileoverview Framework for running JavaScript tests of Polymer elements.
  */
 
 /**
  * Test fixture for Polymer element testing.
@@ skipping 73 matching lines @@
         console.error(msg);
 
         // Mocha will handle the error.
         throw e;
       }
     };
 
     // Import Polymer and iron-test-helpers before running tests.
     suiteSetup(function() {
       var promises = [];
-      if (typeof Polymer != 'function') {
+      if (!window.Polymer) {
         promises.push(
-            PolymerTest.importHtml(
-                'chrome://resources/polymer/v1_0/polymer/polymer.html'));
+            PolymerTest.importHtml('chrome://resources/html/polymer.html'));
       }
       if (typeof MockInteractions != 'object') {
         // Avoid importing the HTML file because iron-test-helpers assumes it is
         // not being imported separately alongside a vulcanized Polymer.
         promises.push(
             PolymerTest.loadScript(
                 'chrome://resources/polymer/v1_0/iron-test-helpers/' +
                 'mock-interactions.js'));
       }
       return Promise.all(promises);
@@ skipping 66 matching lines @@
  */
 PolymerTest.getLibraries = function(basePath) {
   // Ensure basePath ends in '/'.
   if (basePath.length && basePath[basePath.length - 1] != '/')
     basePath += '/';
 
   return PolymerTest.prototype.extraLibraries.map(function(library) {
     return basePath + library;
   });
 };