MD History: Disable individual failing List test rather than entire suite

chrome/test/data/webui/md_history/md_history_browsertest.js

Index: chrome/test/data/webui/md_history/md_history_browsertest.js
diff --git a/chrome/test/data/webui/md_history/md_history_browsertest.js b/chrome/test/data/webui/md_history/md_history_browsertest.js
index 09f84fa97a6bc6a9caeccebaa0b12b2bd406a26b..23de4b2931b54366efae74f0d4ac72ddd1facbf4 100644
--- a/chrome/test/data/webui/md_history/md_history_browsertest.js
+++ b/chrome/test/data/webui/md_history/md_history_browsertest.js
@@ -124,8 +124,7 @@ MaterialHistoryListTest.prototype = {
   ]),
 };
 
-// Test is very flaky on all platforms, http://crbug.com/669227
-TEST_F('MaterialHistoryListTest', 'DISABLED_All', function() {
+TEST_F('MaterialHistoryListTest', 'All', function() {
   mocha.run();
 });