Control flow for loops about infra

[domenic]

HTML uses labels and "goto", but I guess that doesn't work great with foreach-style loops.

[annevk]

Not opposed to both. URL has goto too, although rewrites have been requested for many of the same reasons it's avoided everywhere else...

[mikewest]

CSP uses "continue to the next item" in various places (https://w3c.github.io/webappsec-csp/#parse-serialized-policy for example). Since that's the way it's phrased in a variety of programming languages, phrasing it that way in the spec makes sense to me.

I'd suggest a template like the following:

1. For each |item| in |list|:
   1. If we should skip |item| for some reason, continue to the next |item|.
   2. If we should stop the loop entirely, break.
   3. If we should skip out of this loop to a labeled step, continue to label.
   4. Do a thing to |item|.

[annevk]

I like "continue to label". I wonder if we can just use "continue" for the other kind, since there's no real reason to make that phrase more complicated and mentioning the variable there makes it seem like you're passing an argument (which is a thing we do with "return" and "throw" and "continue to").

And maybe we should have break as well?

If X, then continue.
If Y, then continue to Z.
If AA, then break.

[mikewest]

SGTM.

[annevk]

#56 discusses labels as well so I think we can leave that there for now and consider this fixed by @mikewest. (I'll post a PR for DOM to make use of the new concepts and get rid of the old language.)