Don't fail at startup if textmate grammar can't be parsed by browser

[DanTup]

The textmate grammar uses negative lookbehinds which are not supported in Safari. I've had a go at changing the grammar, but I can't find a way to support what we need (without a significant change to how the textmate grammar works) so for now this change will just handle errors and leave syntax highlighting disabled for browsers that don't support this.

Before this change, DevTools fails to load in safari:

With the change, it loads and prints a warning about the failed syntax highlighting in the console:

And using the app works as normal:

Fixes #2856.

[DanTup]

I believe the bot failure is unrelated (related to the bumping of the SDK version):

The current Dart SDK version is 3.0.0-19.0.dev.
    Because flutter_app depends on cupertino_icons >=0.1.1 <1.0.1 which requires SDK version <2.0.0 or >=2.0.0-dev.28.0 <3.0.0, version solving failed.
    pub get failed

[DanTup]

@elliette should I hold off landing this until bots are green, or is it likely they'll be this way for a while? (I'm less familiar with the process and current status here)

[elliette]

@elliette should I hold off landing this until bots are green, or is it likely they'll be this way for a while? (I'm less familiar with the process and current status here)

@kenzieschmoll for input! I haven't done much devtools development recently

[kenzieschmoll]

I'm trying to fix the bots now - #4941. The breakage is due to the move to Dart version > 3.0.0, since a lot of the packages we depend on have an upper bound sdk constraint of 3.0.0.

[kenzieschmoll]

the temporary fix has landed (#4944). If you merge master, the bots should go green.

[DanTup]

Yep, all green. Thanks!

[DanTup]

@kenzieschmoll @CoderDake I realised I didn't add this to any changelog, and there doesn't seem to be a milestone for the next release. Assuming this should be noted (it makes DevTools load in Safari), is https://github.com/flutter/devtools/blob/master/packages/devtools_app/lib/src/framework/release_notes/release-notes-next.md the correct place to add it? (it looks like it, though there's nothing else currently listed there so I'm unsure if it's just a template).

[kenzieschmoll]

Yes, any notable user facing issues should be documented in the release-notes-next.md file. We automatically generate the CHANGELOG when we do the release, but the release notes should be drafted as we go.

[DanTup]

Thanks - I've opened #4966 to add this.

[wilmarques]

_I was waiting for this so much!!!_
_When will it land?_

Nvm, it is released on 2.21 :)