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/script/test.rs

@@ -15,6 +15,10 @@ pub mod area {
     pub use dom::htmlareaelement::{Area, Shape};
 }
 
+pub mod sizes {
+    pub use dom::htmlimageelement::{parse_a_sizes_attribute, Size};
+}
+
 pub mod size_of {
     use dom::characterdata::CharacterData;
     use dom::element::Element;