Auto merge of #18714 - jdm:sizes, r=jdm

Parse sizes attribute values

Squashed version of #17808.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix (partially) #11416
- [x] There are tests for these changes

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components/style/servo/media_queries.rs

@@ -164,7 +164,7 @@ pub enum ExpressionKind {
 /// http://dev.w3.org/csswg/mediaqueries-3/#media1
 #[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-pub struct Expression(ExpressionKind);
+pub struct Expression(pub ExpressionKind);
 
 impl Expression {
     /// The kind of expression we're, just for unit testing.