servo: Merge #16141 - style: Add <keyword>::from_ident helper to avoid tokenizing the same value multiple times (from emilio:keyword-from-ident); r=nox

We can use this to avoid tokenizing multiple times in some places, like #16127.

Source-Repo: https://github.com/servo/servo
Source-Revision: 447742b0a70395e55d6d1518fa51ad5b190abc8c

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 25adf3ad8feae17a3038424f4c9274d44c54fc58

servo/components/style_traits/values.rs

@@ -117,7 +117,12 @@ macro_rules! __define_css_keyword_enum__actual {
             /// Parse this property from a CSS input stream.
             pub fn parse(input: &mut ::cssparser::Parser) -> Result<$name, ()> {
                 let ident = input.expect_ident()?;
-                match_ignore_ascii_case! { &ident,
+                Self::from_ident(&ident)
+            }
+
+            /// Parse this property from an already-tokenized identifier.
+            pub fn from_ident(ident: &str) -> Result<$name, ()> {
+                match_ignore_ascii_case! { ident,
                                            $( $css => Ok($name::$variant), )+
                                            _ => Err(())
                 }