Disable tabs.relativeUrlTabsUpdate ran in ExtensionApiTest.Tabs until it beco...

chrome/test/data/extensions/api_test/tabs/test.js

Index: chrome/test/data/extensions/api_test/tabs/test.js
===================================================================
--- chrome/test/data/extensions/api_test/tabs/test.js	(revision 26190)
+++ chrome/test/data/extensions/api_test/tabs/test.js	(working copy)
@@ -348,13 +348,14 @@
     );
   },
 
+  /* FIXME: Bug 21851. Make this test item not flaky.
   function relativeUrlTabsUpdate() {
     chrome.tabs.update(testTabId, {url: "chrome://a/"}, function(tab) {
       chrome.test.assertEq("chrome://a/", tab.url);
       chrome.tabs.update(tab.id, {url: "relative.html"}, function(tab) {  
       });
     });
-  },
+  }, */
   
   function relativeUrlWindowsCreate() {
     chrome.windows.create({url: "relative.html"});