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

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

Index: chrome/test/data/webui/md_history/history_list_test.js
diff --git a/chrome/test/data/webui/md_history/history_list_test.js b/chrome/test/data/webui/md_history/history_list_test.js
index 55cbb8a0140cd94d35a2ac157494af43a7ffee97..687cd09ffd319c301ba1c32b1cb24026d85aaf93 100644
--- a/chrome/test/data/webui/md_history/history_list_test.js
+++ b/chrome/test/data/webui/md_history/history_list_test.js
@@ -497,7 +497,8 @@ suite('<history-list>', function() {
     });
   });
 
-  test('focus and keyboard nav', function(done) {
+  // Test is very flaky on all platforms, http://crbug.com/669227.
+  test.skip('focus and keyboard nav', function(done) {
     app.historyResult(createHistoryInfo(), TEST_HISTORY_RESULTS);
     PolymerTest.flushTasks().then(function() {
       var items = polymerSelectAll(element, 'history-item');