[CSS] Add support for at-scope rule

[deathaxe]

Resolves #3867

This commit implements support for @scope rules.

see: https://developer.mozilla.org/en-US/docs/Web/CSS/@scope

Notes: At the time of writing it is an experimental feature not supported by all major browsers.

[thecodechef]

This is Screenshot of your syntax tests when i see it from my end

the .limit > * part is highlighted but the .class is not thats what i mean by that

[deathaxe]

How is Github's syntax not supporting this new experimental feature related with the fix for ST's syntax definition?

[thecodechef]

Because when I also use it in the latest stable build I get the same behavior

[deathaxe]

CSS has significanty changed since ST4152. Hence, you'd need to replace the whole CSS.sublime-syntax file. It may however have effects on 3rd-party syntaxes such as Less as those may need some tweaks to follow these changes.

[thecodechef]

Which is what I did I extracted Packages/CSS using PackageResourcwViewer then copied your version and replaced the other

[deathaxe]

As all CI tests (against ST4143 and ST4165) are passing it must be an issue on your end.

[thecodechef]

That may be true, but tests can always send false positives. I have been using Sublime Text ever since Sublime Text 2 I'm not new. & furthermore it was when I changed your code thats it started working like it should

[deathaxe]

As test results are equal with what I see, when symlinking this branch into a vanilla ST4152 portable setup's Packages folder, I tend to trust them.

The only "inaccuracy" this branch has, is allowing arbritary ammounts of () to () to () ..., which however shouldn't hurt in real world.

[thecodechef]

push:
  - include: at-scope-content-keywords
  - include: at-scope-selector

Is what I meant in that comment

[deathaxe]

Note: @scope is supported by all major browsers and no longer marked experimental.