Fix polymer 2 tests

Bug: Issue 10930
Change-Id: Ie19714c66ec4941de816976761abac1faa534386

polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.html

@@ -267,7 +267,15 @@ limitations under the License.
       element.path = 'some/path';
       element.projectName = 'Some project';
       const threadEls = threads.map(
-          thread => element._createThreadElement(thread));
+          thread => {
+            const threadEl = element._createThreadElement(thread);
+            // Polymer 2 doesn't fire ready events and doesn't execute
+            // observers if element is not added to the Dom.
+            // See https://github.com/Polymer/old-docs-site/issues/2322
+            // and https://github.com/Polymer/polymer/issues/4526
+            element._attachThreadElement(threadEl);
+            return threadEl;
+          });
       assert.equal(threadEls.length, 2);
       assert.equal(threadEls[0].rootId, 4711);
       assert.equal(threadEls[1].rootId, 42);

polygerrit-ui/app/elements/gr-app_test.html

@@ -24,7 +24,13 @@ limitations under the License.
 <script src="/bower_components/webcomponentsjs/webcomponents-lite.js"></script>
 <script src="/bower_components/web-component-tester/browser.js"></script>
 <link rel="import" href="../test/common-test-setup.html"/>
-<link rel="import" href="gr-app.html">
+
+<script>
+  const link = document.createElement('link');
+  link.setAttribute('rel', 'import');
+  link.setAttribute('href', window.POLYMER2 ? 'gr-app-p2.html' : 'gr-app.html');
+  document.head.appendChild(link);
+</script>
 
 <script>void(0);</script>
 
@@ -34,6 +40,12 @@ limitations under the License.
   </template>
 </test-fixture>
 
+<test-fixture id="basic-p2">
+  <template>
+    <gr-app-p2 id="app"></gr-app-p2>
+  </template>
+</test-fixture>
+
 <script>
   suite('gr-app tests', () => {
     let sandbox;
@@ -68,7 +80,7 @@ limitations under the License.
         probePath() { return Promise.resolve(42); },
       });
 
-      element = fixture('basic');
+      element = fixture(window.POLYMER2 ? 'basic-p2' : 'basic');
       flush(done);
     });