Fix CSSStyleDeclaration's item() to provide properties instead of values (#31299)

For example,

    style.cssText = "margin: 1px 2px 3px 4px";
    [...style];

will now be

    ["margin-top", "margin-right", "margin-bottom", "margin-left"]

instead of

    ["1px", "2px", "3px", "4px"]

components/script/dom/cssstyledeclaration.rs

@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use cssparser::CssStringWriter;
 use dom_struct::dom_struct;
 use html5ever::local_name;
 use servo_arc::Arc;
@@ -14,7 +15,7 @@ use style::properties::{
 use style::selector_parser::PseudoElement;
 use style::shared_lock::Locked;
 use style::stylesheets::{CssRuleType, Origin};
-use style_traits::ParsingMode;
+use style_traits::{CssWriter, ParsingMode, ToCss};
 
 use crate::dom::bindings::codegen::Bindings::CSSStyleDeclarationBinding::CSSStyleDeclarationMethods;
 use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
@@ -431,13 +432,11 @@ impl CSSStyleDeclarationMethods for CSSStyleDeclaration {
     fn IndexedGetter(&self, index: u32) -> Option<DOMString> {
         self.owner.with_block(|pdb| {
             let declaration = pdb.declarations().get(index as usize)?;
-            let important = pdb.declarations_importance().get(index as usize)?;
+            let mut dest = String::new();
-            let mut css = String::new();
+            let mut writer = CssStringWriter::new(&mut dest);
-            declaration.to_css(&mut css).unwrap();
+            let mut writer = CssWriter::new(&mut writer);
-            if important {
+            declaration.id().to_css(&mut writer).ok()?;
-                css += " !important";
+            Some(DOMString::from(dest))
-            }
-            Some(DOMString::from(css))
         })
     }
 

tests/wpt/meta-legacy-layout/css/css-variables/variable-invalidation.html.ini

@@ -1,13 +0,0 @@
-[variable-invalidation.html]
-  [css rule test]
-    expected: FAIL
-
-  [css rule test important]
-    expected: FAIL
-
-  [inline style test]
-    expected: FAIL
-
-  [inline style test important]
-    expected: FAIL
-

tests/wpt/meta-legacy-layout/css/cssom/css-style-declaration-modifications.html.ini

@@ -1,3 +0,0 @@
-[css-style-declaration-modifications.html]
-  bug: https://github.com/servo/servo/issues/21579
-  expected: TIMEOUT

tests/wpt/meta-legacy-layout/css/cssom/cssom-getPropertyValue-common-checks.html.ini

@@ -1,18 +1,3 @@
 [cssom-getPropertyValue-common-checks.html]
   [All properties (except 'all') can serialize their initial value (computed)]
     expected: FAIL
-
-  [All shorthands can serialize their longhands set to 'initial']
-    expected: FAIL
-
-  [All aliases can serialize target property set to 'initial']
-    expected: FAIL
-
-  [Can't serialize shorthand when longhands are set to different css-wide keywords]
-    expected: FAIL
-
-  [Can't serialize shorthand when longhands have different priority]
-    expected: FAIL
-
-  [Can't serialize shorthand set to 'initial' when some longhand is missing]
-    expected: FAIL

tests/wpt/meta-legacy-layout/css/cssom/cssstyledeclaration-custom-properties.html.ini

@@ -1,4 +0,0 @@
-[cssstyledeclaration-custom-properties.html]
-  [Custom properties are included in computed style]
-    expected: FAIL
-

tests/wpt/meta-legacy-layout/css/cssom/cssstyledeclaration-setter-declarations.html.ini

@@ -1,13 +0,0 @@
-[cssstyledeclaration-setter-declarations.html]
-  [setProperty with longhand should update only the declaration being set]
-    expected: FAIL
-
-  [property setter should update only the declaration being set]
-    expected: FAIL
-
-  [setProperty with shorthand should update only the declarations being set]
-    expected: FAIL
-
-  [longhand property setter should update only the decoarations being set]
-    expected: FAIL
-

tests/wpt/meta-legacy-layout/css/cssom/cssstyledeclaration-setter-logical.html.ini

@@ -1,4 +0,0 @@
-[cssstyledeclaration-setter-logical.html]
-  [newly set declaration should be after all declarations in the same logical property group but have different logical kind]
-    expected: FAIL
-

tests/wpt/meta-legacy-layout/css/cssom/inline-style-001.html.ini

@@ -1,3 +0,0 @@
-[inline-style-001.html]
-  bug: https://github.com/servo/servo/issues/21579
-  expected: TIMEOUT

tests/wpt/meta-legacy-layout/css/cssom/serialize-all-longhands.html.ini

@@ -1,6 +1,3 @@
 [serialize-all-longhands.html]
-  [Specified style]
-    expected: FAIL
-
   [Computed style]
     expected: FAIL

tests/wpt/meta-legacy-layout/css/cssom/variable-names.html.ini

@@ -1,19 +1,6 @@
 [variable-names.html]
-  [custom property '--a']
-    expected: FAIL
-
   [custom property '--a;b']
     expected: FAIL
 
-  [custom property '---']
-    expected: FAIL
-
   [custom property '--\\']
     expected: FAIL
-
-  [custom property '--ab']
-    expected: FAIL
-
-  [custom property '--0']
-    expected: FAIL
-

tests/wpt/meta/css/css-variables/variable-invalidation.html.ini

@@ -1,13 +0,0 @@
-[variable-invalidation.html]
-  [css rule test]
-    expected: FAIL
-
-  [css rule test important]
-    expected: FAIL
-
-  [inline style test]
-    expected: FAIL
-
-  [inline style test important]
-    expected: FAIL
-

tests/wpt/meta/css/cssom/css-style-declaration-modifications.html.ini

@@ -1,2 +0,0 @@
-[css-style-declaration-modifications.html]
-  expected: TIMEOUT

tests/wpt/meta/css/cssom/cssom-getPropertyValue-common-checks.html.ini

@@ -2,17 +2,5 @@
   [All properties (except 'all') can serialize their initial value (computed)]
     expected: FAIL
 
-  [All shorthands can serialize their longhands set to 'initial']
+  [All shorthands (except 'all') can serialize their longhands set to their initial value]
-    expected: FAIL
-
-  [All aliases can serialize target property set to 'initial']
-    expected: FAIL
-
-  [Can't serialize shorthand when longhands are set to different css-wide keywords]
-    expected: FAIL
-
-  [Can't serialize shorthand when longhands have different priority]
-    expected: FAIL
-
-  [Can't serialize shorthand set to 'initial' when some longhand is missing]
     expected: FAIL

tests/wpt/meta/css/cssom/cssstyledeclaration-custom-properties.html.ini

@@ -1,4 +0,0 @@
-[cssstyledeclaration-custom-properties.html]
-  [Custom properties are included in computed style]
-    expected: FAIL
-

tests/wpt/meta/css/cssom/cssstyledeclaration-setter-declarations.html.ini

@@ -1,13 +0,0 @@
-[cssstyledeclaration-setter-declarations.html]
-  [setProperty with longhand should update only the declaration being set]
-    expected: FAIL
-
-  [longhand property setter should update only the decoarations being set]
-    expected: FAIL
-
-  [property setter should update only the declaration being set]
-    expected: FAIL
-
-  [setProperty with shorthand should update only the declarations being set]
-    expected: FAIL
-

tests/wpt/meta/css/cssom/cssstyledeclaration-setter-logical.html.ini

@@ -1,4 +0,0 @@
-[cssstyledeclaration-setter-logical.html]
-  [newly set declaration should be after all declarations in the same logical property group but have different logical kind]
-    expected: FAIL
-

tests/wpt/meta/css/cssom/inline-style-001.html.ini

@@ -1,2 +0,0 @@
-[inline-style-001.html]
-  expected: TIMEOUT

tests/wpt/meta/css/cssom/serialize-all-longhands.html.ini

@@ -1,6 +0,0 @@
-[serialize-all-longhands.html]
-  [Specified style]
-    expected: FAIL
-
-  [Computed style]
-    expected: FAIL

tests/wpt/meta/css/cssom/variable-names.html.ini

@@ -1,19 +1,6 @@
 [variable-names.html]
-  [custom property '--a']
-    expected: FAIL
-
-  [custom property '---']
-    expected: FAIL
-
-  [custom property '--ab']
-    expected: FAIL
-
-  [custom property '--0']
-    expected: FAIL
-
   [custom property '--a;b']
     expected: FAIL
 
   [custom property '--\\']
     expected: FAIL
-