Bug 1434590 - Re-enabled browser_ext_tabs_lastAccessed.js test on Windows. r=jmaher

This test has been disabled because it was failing intermittently with a pretty high
frequency on the Windows platform, the reasons behind the failures have been fixed
in Bug 1435100.

MozReview-Commit-ID: FNJqocBcxnf

--HG--
extra : rebase_source : f5fd1392bc53f137c8e48e433fddd103af74eaad

browser/components/extensions/test/browser/browser-common.ini

@@ -167,7 +167,6 @@ skip-if = !e10s
 [browser_ext_tabs_hide_update.js]
 [browser_ext_tabs_insertCSS.js]
 [browser_ext_tabs_lastAccessed.js]
-skip-if = os == 'win' # Bug 1434590
 [browser_ext_tabs_lazy.js]
 [browser_ext_tabs_removeCSS.js]
 [browser_ext_tabs_move_array.js]