Bug 1593544 - disable failing test_bootstrap.js. rs=bustage-fix

common/test/xpcshell/xpcshell.ini

@@ -5,6 +5,7 @@ support-files =
   data/**
 
 [test_bootstrap.js]
+skip-if = true # See bug 1593544.
 [test_bootstrap_const.js]
 [test_bootstrap_globals.js]
 [test_bootstrapped_chrome_manifest.js]