Bug 1435394 - disable browser_upgrade_backup.js on windows for frequent failures. r=jmaher

browser/components/sessionstore/test/browser.ini

@@ -131,7 +131,7 @@ support-files =
 [browser_switch_remoteness.js]
 run-if = e10s
 [browser_upgrade_backup.js]
-skip-if = (os == 'linux' && (asan || debug)) || (verify && debug && (os == 'mac')) # Bug 1435394 disabled on Linux
+skip-if = (os == 'linux' && (asan || debug)) || (verify && debug && (os == 'mac')) || (os == 'win' && bits == 64) # Bug 1435394 disabled on Linux and Windows
 [browser_windowRestore_perwindowpb.js]
 [browser_248970_b_perwindowpb.js]
 # Disabled because of leaks.