Auto merge of #20191 - jfkthame:font-shorthand-resets-variation-settings, r=emilio

style: Make 'font' shorthand reset 'font-variation-settings' property

As required by the spec: https://drafts.csswg.org/css-fonts-4/#font-prop

See https://bugzilla.mozilla.org/show_bug.cgi?id=1435983

Basically, make font-variation-settings work in the same way as font-feature-settings
already does.

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

- [ ] There are tests for these changes OR
- [X] These changes do not require tests because font-variation-settings isn't supported in servo; it is implemented here for gecko/stylo, and will be tested by mozilla-central mochitests.

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ports/geckolib/glue.rs

@@ -4857,7 +4857,7 @@ pub extern "C" fn Servo_ParseFontDescriptor(
     use style::font_face::{FontDisplay, FontWeight, Source};
     use style::properties::longhands::font_language_override;
     use style::values::computed::font::FamilyName;
-    use style::values::specified::font::{SpecifiedFontFeatureSettings, FontVariationSettings};
+    use style::values::specified::font::{SpecifiedFontFeatureSettings, SpecifiedFontVariationSettings};
 
     let string = unsafe { (*value).to_string() };
     let mut input = ParserInput::new(&string);
@@ -4907,7 +4907,7 @@ pub extern "C" fn Servo_ParseFontDescriptor(
             eCSSFontDesc_Src / Vec<Source>,
             eCSSFontDesc_UnicodeRange / Vec<UnicodeRange>,
             eCSSFontDesc_FontFeatureSettings / SpecifiedFontFeatureSettings,
-            eCSSFontDesc_FontVariationSettings / FontVariationSettings,
+            eCSSFontDesc_FontVariationSettings / SpecifiedFontVariationSettings,
             eCSSFontDesc_FontLanguageOverride / font_language_override::SpecifiedValue,
             eCSSFontDesc_Display / FontDisplay,
         ]

ports/geckolib/tests/size_of.rs

@@ -40,7 +40,7 @@ size_of_test!(test_size_of_rule_node, RuleNode, 80);
 
 // This is huge, but we allocate it on the stack and then never move it,
 // we only pass `&mut SourcePropertyDeclaration` references around.
-size_of_test!(test_size_of_parsed_declaration, style::properties::SourcePropertyDeclaration, 576);
+size_of_test!(test_size_of_parsed_declaration, style::properties::SourcePropertyDeclaration, 608);
 
 size_of_test!(test_size_of_computed_image, computed::image::Image, 40);
 size_of_test!(test_size_of_specified_image, specified::image::Image, 40);