Implement ES6 @@toString

[classilla]

Not in current Firefox.

default-src 'none'; base-uri 'self'; connect-src 'self' uploads.github.com status.github.com collector.githubapp.com api.github.com www.google-analytics.com github-cloud.s3.amazonaws.com wss://live.github.com; font-src assets-cdn.github.com; form-action 'self' github.com gist.github.com; frame-ancestors 'none'; frame-src render.githubusercontent.com; img-src 'self' data: assets-cdn.github.com identicons.github.com collector.githubapp.com github-cloud.s3.amazonaws.com *.githubusercontent.com; media-src 'none'; script-src assets-cdn.github.com; style-src 'unsafe-inline' assets-cdn.github.com


22:32:57.291 Content Security Policy: The page's settings blocked the loading of a resource at self ("script-src https://assets-cdn.github.com").1 frameworks-b656af906df0ec252f7683ae76db8ed358bf5b309bd5781fc467ae3c1d571c2a.js:1:0


<script crossorigin="anonymous" integrity="sha256-tlavkG3w7CUvdoOudtuO01i/WzCb1XgfxGeuPB1XHCo=" src="https://assets-cdn.github.com/assets/frameworks-b656af906df0ec252f7683ae76db8ed358bf5b309bd5781fc467ae3c1d571c2a.js"></script>

[classilla]

It looks like the script being loaded incorrectly is seen as 'self' when it is, in fact, being loaded from the specified host.

[classilla]

It's because it's running a script which is evalled into a Function. This is presumably fixed by https://bugzilla.mozilla.org/show_bug.cgi?id=1114580 .

[classilla]

Github seems to have fixed this but we still want this anyway because it may well occur again.

[classilla]

M1114580 can be implemented without the ESClass changes which considerably simplifies it.

[classilla]

This works and passes tests with a tweak to allow the old Proxy.create() syntax to pass tests as well.