feat: support @container

[yisibl]

• Safari Technology Preview 142 has container queries enabled.
• https://caniuse.com/css-container-queries
• https://drafts.csswg.org/css-contain-3/#container-rule

Input

@supports ( container-type: size ) {
  @container ( width <= 150px ) {
    #inner {
      background-color: skyblue;
    }
  }
}

Output

@supports (container-type: size){@container (width <= 150px){#inner{background-color:#87ceeb}}}

[yisibl]

@evanw PTAL, thanks.

[yisibl]

Thanks!