Remove an exact-error-message check from an xpcshell test -- error message string format is not a stable interface, and tests shouldn't break when message strings change from time to time. Followup to bug 507998, r=orange

--HG--
extra : rebase_source : b30fe2c6dc49c3278e1177bee7e55b6ee833dac6

services/sync/tests/unit/test_service_getStorageInfo.js

@@ -83,7 +83,6 @@ add_test(function test_invalid_json() {
 
   let request = Service.getStorageInfo(INFO_COLLECTIONS, function (error, info) {
     do_check_eq(error.name, "SyntaxError");
-    do_check_eq(error.message, "JSON.parse: unexpected character");
     do_check_eq(info, null);
     server.stop(run_next_test);
   });