- Make URLSearchParams constructor spec-compliant
- Strip leading `?` in URL#search's setter
- Spec-compliant iterable interface
- More precise handling of update steps as mandated by the spec
- Add class strings to URLSearchParams objects and their prototype
- Make sure `this instanceof URLSearchParams` in methods
Also included are relevant tests from W3C's Web Platform Tests
(https://github.com/w3c/web-platform-tests/tree/master/url).
Fixes: https://github.com/nodejs/node/issues/9302
PR-URL: https://github.com/nodejs/node/pull/9484
Reviewed-By: James M Snell <jasnell@gmail.com>
