Format SCSS maps like CSS rules

[asmockler]

Resolves #3056

This makes prettier format SCSS maps like CSS rules (line breaks after each rule). e.g.

$map: (color: #111111, text-shadow: 1px 1px 0 salmon)

will format to

$map: (
  color: #111111,
  text-shadow: 1px 1px 0 salmon
);

[lydell]

As you've probably noticed, the AST nodes in CSS/SCSS/Less are super vague and super general. While this PR looks good, I'm worried about what unintended side effects this might/will have. Our tests aren't very comprehensive. But I guess we could also just release it and do the regular couple of point releases afterwards with CSS regression fixes ¯\_(ツ)_/¯

[asmockler]

Would it help if we checked startsWith('$') on the parent value? If that doesn't give any more assurance, I am fine fielding any regressions that arise related to this.

[azz]

I think the startsWith check is a good idea, but otherwise LGTM.

[asmockler]

Added the startsWith check; it now reaches up 2 nodes and checks for a css-decl+ startsWith("$") instead of just value-value 👍

[azz]

Might want to be a bit defensive and prefix with declaration && . It might not exist?

[asmockler]

Good call - just updated.

[azz]

Thanks!