Bug 1277107 - Skip browser_UITour_heartbeat.js on Windows where it fails constantly

browser/components/uitour/test/browser.ini

@@ -31,6 +31,7 @@ skip-if = os == "linux" # Linux: Bug 986760, Bug 989101.
 [browser_UITour_detach_tab.js]
 [browser_UITour_forceReaderMode.js]
 [browser_UITour_heartbeat.js]
+skip-if = os == "win" # Bug 1277107
 [browser_UITour_modalDialog.js]
 skip-if = os != "mac" # modal dialog disabling only working on OS X.
 [browser_UITour_observe.js]