Bug 1736459 - Disable test_crash_backgroundtask_moz_crash.js on Windows. r=gsvelto

Differential Revision: https://phabricator.services.mozilla.com/D129493

toolkit/crashreporter/test/unit/xpcshell.ini

@@ -40,6 +40,8 @@ skip-if = (os != 'win' && os != 'linux') || (os=='linux' && bits==32)
 [test_crash_terminator.js]
 
 [test_crash_backgroundtask_moz_crash.js]
+skip-if = os == 'win'
+reason = Race condition that makes it fail too frequently
 
 [test_crash_heap_corruption.js]
 skip-if = os != 'win'