fix: CSS-wide keywords and none in @keyframes cannot remove quotes

[yisibl]

In the @keyframes rule, this is an invalid syntax if the <keyframes-name> is CSS-wide keywords or none keyword.

<keyframes-name> = <custom-ident> | <string>

Before this PR, we would always remove the quotes, which would result in generating an invalid CSS if the quotes happened to be CSS-wide keywords.

CSS-wide keywords =  initial | inherit | unset | default | revert | revert-layer

Before

/* Input */
@keyframes "revert" {}
@keyframes "none" {}

/* Output */
@keyframes revert {}
@keyframes none {}

After

/* Input */
@keyframes "revert" {}
@keyframes "none" {}

/* Output */
@keyframes "revert" {}
@keyframes "none" {}

Throw an error

With the new parsing method, the following cases will throw an error, which was previously considered a legal CSS rule.

/* Input */
@keyframes revert {}
@keyframes none {}

/* Output */
Unexpected token Ident("revert")
Unexpected token Ident("none")

[devongovett]

Thanks! We'll need to update AnimationName in properties/animation.rs the same way as KeyframesName.

[devongovett]

This will result in the name being quoted/escaped, but the unused_symbols list won't be. You'll need to do a match on the keyframe name to pull out the embedded string.

[yisibl]

We'll need to update AnimationName in properties/animation.rs the same way as KeyframesName.

Can I fix it in the next PR? Here I want to focus on @keyframes.