Enable tests related to the extensions web ui that were flaky.

chrome/test/data/webui/test_api.js

Index: chrome/test/data/webui/test_api.js
diff --git a/chrome/test/data/webui/test_api.js b/chrome/test/data/webui/test_api.js
index be8664310a231be58f9744c91e67ac0f509155e3..f528322c2614612cd6827f1ba890a6cb1b870e0b 100644
--- a/chrome/test/data/webui/test_api.js
+++ b/chrome/test/data/webui/test_api.js
@@ -44,6 +44,23 @@ var testing = {};
    */
   function Test() {};
 
+  /**
+   * Make all transitions and animations take 0ms.
+   * Any animations will still happen and webkit-animation-end should be
+   * listened to.

[Dan Beam, 2015/04/30 23:01:54]

please note here that no transition end events will work while this style is
applied

[hcarmona, 2015/04/30 23:16:59]

Done.

+   */
+  Test.disableAnimationsAndTransitions = function() {
+    var noAnimationStyle = document.createElement('style');

[Dan Beam, 2015/04/30 23:01:54]

noAnimationStyle.id = 'no-animation';

[hcarmona, 2015/04/30 23:16:59]

Done.

+    noAnimationStyle.textContent =
+      '* {' +
+      '  -webkit-transition-duration: 0ms !important;' +
+      '  -webkit-transition-delay: 0ms !important;' +
+      '  -webkit-animation-duration: 0ms !important;' +
+      '  -webkit-animation-delay: 0ms !important;' +
+      '}';
+    document.querySelector('head').appendChild(noAnimationStyle);
+  };
+
   Test.prototype = {
     /**
      * The name of the test.