Enables the `service-worker` tests on Saucelabs and fixes some issues that were preventing them from running on IE. The issues were:
1. We were serving es2017 code during tests. I've set it to es5.
2. The check which was verifying whether the environment is supported ended up hitting a `require` call in the browser which caused it to fail on browsers that don't support the `URL` API.
PR Close#36129