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 72 matching lines @@
           msg += '  ' + PolymerTest.scriptUrls_[i] + '\n';
         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') {

[michaelpg, 2016/04/05 00:49:42]

maybe keep this as 
    if (!Polymer) {

-        promises.push(
-            PolymerTest.importHtml(
-                'chrome://resources/polymer/v1_0/polymer/polymer.html'));
-      }
+      var promises = [
+        PolymerTest.importHtml('chrome://resources/html/polymer.html'),

[michaelpg, 2016/04/05 00:49:42]

this assumes the page being tested doesn't load
    <script src="chrome://resources/js/polymer_config.js"></script>

which is untrue for pages that don't use chrome://resources/html/polymer.html,
like MediaRouter (this will cause MediaRouterElementsBrowserTest to fail)

[Dan Beam, 2016/04/05 01:38:58]

why doesn't media router stuff use 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 65 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;
   });
 };