Deprecate the filename option

[lydell]

Why?

• It is only used to set the file property of the source map, and
  that’s probably done just because the file property used to be a
  required property of source maps. It isn’t no more.
• The file property is not used by browsers.
• The user could easily just add the property himself on the returned
  source map object.
• It was neither documented nor tested.
• KISS.

[conradz]

I think if we decide to deprecate filename, we can just remove it altogether and bump major version.

[jonathanong]

@lydell yo i noticed a lot of PRs you've made and appreciate them. @necolas is considering merging these two libraries in to css so maintenance would be easier: reworkcss/css#13. i think doing all this source map stuff after we merged these libraries would be easier.

[conradz]

@jonathanong woops, hadn't noticed that issue, 👍 on it anyways.

[necolas]

I'm happy to merge the libraries whenever it's easiest for everyone else. I was thinking we'd do it once things stabilized just before new releases, but if you'd prefer to merge them before finalizing the source mapping, that's cool too. lmk

[jonathanong]

Doesn't matter to me, I just think it might be easier to merge them now

[conradz]

Ya, I think it might be better to merge now. No big deal either way though.

[lydell]

I think if we decide to deprecate filename, we can just remove it altogether and bump major version.

Ok, closing this then.

---

It doesn’t matter to me either. There’s no rush merging any PRs, and I could submit new ones after the merge if needed.

[necolas]

OK I've merged things into reworkcss/css. Feel free to develop against that and port over any existing issues.

[lydell]

reworkcss/css#26