Updating custom element test to only load polyfill when needed.

pkg/custom_element/test/custom_element_test.dart

Index: pkg/custom_element/test/custom_element_test.dart
diff --git a/pkg/custom_element/test/custom_element_test.dart b/pkg/custom_element/test/custom_element_test.dart
index 341713aa364db6f061643e4c0b43f6a588efa2c2..3094518494192ce1837f94cd628a54a416ae2c55 100644
--- a/pkg/custom_element/test/custom_element_test.dart
+++ b/pkg/custom_element/test/custom_element_test.dart
@@ -13,16 +13,16 @@ import 'package:unittest/unittest.dart';
 main() {
   useHtmlConfiguration();
 
-  // Load the MutationObserver polyfill.
-  HttpRequest.getString('/root_dart/pkg/mutation_observer/lib/'
-      'mutation_observer.js').then((code) {
-    document.head.children.add(new ScriptElement()..text = code);
-
-    customElementTests();
+  setUp(() {
+    // Load the MutationObserver polyfill if needed.
+    if (!MutationObserver.supported) {
+      var script = new ScriptElement()
+          ..src =  '/packages/mutation_observer/mutation_observer.js';
+      document.head.append(script);
+      return script.onLoad.first;

[Jennifer Messerly, 2013/09/12 20:43:48]

Nice! This blocks the test until it loads? That was the bit I was missing, hence
used ".text" as a hacky workaround :)

Can enable CSP testing now with this fix?

[blois, 2013/09/12 21:23:13]

The setUp function handles Future return types just like tests. Primary benefit
of this approach is that mutation_observer.js appears in your sources list and
makes it easier to navigate.

CSP does not allow programmatic insertion of script tags, so no.

+    }
   });
-}
 
-customElementTests() {
   test('register creates the element and calls lifecycle methods', () {
     // Add element to the page.
     var element = new Element.html('<fancy-button>foo bar</fancy-button>',