Implement the named properties object for global

[Sebmaster]

TODO:

• [ ] [LegacyUnenumerableNamedProperties]

[domenic]

In general we need to run tests to make sure adding a proxy in the global prototype chain doesn't massively slow down everything.

The best benchmark I've found is to clone tc39/ecma262, do time node_modules/.bin/ecmarkup--verbose spec.html out/index.html, then force install a version of jsdom patched appropriately, and do it again. We shouldn't regress by more than a few seconds.