Material PDF: Drastically reduce time required to stamp complex bookmark trees

chrome/test/data/pdf/material_elements_test.js

Index: chrome/test/data/pdf/material_elements_test.js
diff --git a/chrome/test/data/pdf/material_elements_test.js b/chrome/test/data/pdf/material_elements_test.js
index fdcc2fa87db485de797b4781c15505bf15d25003..4db7c5619b6df23b5f2a2234415778ed28f5a4f1 100644
--- a/chrome/test/data/pdf/material_elements_test.js
+++ b/chrome/test/data/pdf/material_elements_test.js
@@ -109,6 +109,9 @@ var tests = [
         bookmarkContent.shadowRoot.querySelectorAll('viewer-bookmark');
     chrome.test.assertEq(1, rootBookmarks.length, "one root bookmark");
     var rootBookmark = rootBookmarks[0];
+    MockInteractions.tap(rootBookmark.$.expand);
+
+    Polymer.dom.flush();
 
     var subBookmarks =
         rootBookmark.shadowRoot.querySelectorAll('viewer-bookmark');
@@ -127,14 +130,6 @@ var tests = [
     MockInteractions.tap(subBookmarks[1].$.item);
     chrome.test.assertEq(3, lastPageChange);
 
-    var subBookmarkDiv =
-        rootBookmark.shadowRoot.querySelector('.sub-bookmark');
-
-    chrome.test.assertTrue(subBookmarkDiv.hidden);
-    MockInteractions.tap(rootBookmark.$.expand);
-    chrome.test.assertFalse(subBookmarkDiv.hidden);
-    chrome.test.assertEq('hidden', subBookmarks[1].$.expand.style.visibility);
-
     chrome.test.succeed();
   },