Rollup merge of rust-lang#82545 - jsha:woff2, r=GuillaumeGomez

rustdoc: add optional woff2 versions of FiraSans.

For browsers that support woff2 (most modern ones:
https://caniuse.com/woff2), this offers a reduction in download size
for these two fonts from 362k to 257k (32% reduction). It decreases the
total page size for `struct.String.html` (counting all subresources) by
about 2.5%.

If this is interesting, I'm happy to apply the same treatment to the
other fonts, but these two are the biggest.

Author: GuillaumeGomez

src/librustdoc/html/render/mod.rs

@@ -883,6 +883,8 @@ themePicker.onblur = handleThemeButtonsBlur;
         static_files::NORMALIZE_CSS,
         options.enable_minification,
     )?;
+    write(cx.dst.join("FiraSans-Regular.woff2"), static_files::fira_sans::REGULAR2)?;
+    write(cx.dst.join("FiraSans-Medium.woff2"), static_files::fira_sans::MEDIUM2)?;
     write(cx.dst.join("FiraSans-Regular.woff"), static_files::fira_sans::REGULAR)?;
     write(cx.dst.join("FiraSans-Medium.woff"), static_files::fira_sans::MEDIUM)?;
     write(cx.dst.join("FiraSans-LICENSE.txt"), static_files::fira_sans::LICENSE)?;

src/librustdoc/html/static/FiraSans-Medium.woff2

@@ -3,13 +3,17 @@
 	font-family: 'Fira Sans';
 	font-style: normal;
 	font-weight: 400;
-	src: local('Fira Sans'), url("FiraSans-Regular.woff") format('woff');
+	src: local('Fira Sans'),
+		url("FiraSans-Regular.woff2") format("woff2"),
+		url("FiraSans-Regular.woff") format('woff');
 }
 @font-face {
 	font-family: 'Fira Sans';
 	font-style: normal;
 	font-weight: 500;
-	src: local('Fira Sans Medium'), url("FiraSans-Medium.woff") format('woff');
+	src: local('Fira Sans Medium'),
+		url("FiraSans-Medium.woff2") format("woff2"),
+		url("FiraSans-Medium.woff") format('woff');
 }
 
 /* See SourceSerifPro-LICENSE.txt for the Source Serif Pro license. */

src/librustdoc/html/static/FiraSans-Regular.woff2

@@ -76,9 +76,15 @@ crate mod fira_sans {
     /// The file `FiraSans-Regular.woff`, the Regular variant of the Fira Sans font.
     crate static REGULAR: &[u8] = include_bytes!("static/FiraSans-Regular.woff");
 
+    /// The file `FiraSans-Regular.woff2`, the Regular variant of the Fira Sans font in woff2.
+    crate static REGULAR2: &[u8] = include_bytes!("static/FiraSans-Regular.woff2");
+
     /// The file `FiraSans-Medium.woff`, the Medium variant of the Fira Sans font.
     crate static MEDIUM: &[u8] = include_bytes!("static/FiraSans-Medium.woff");
 
+    /// The file `FiraSans-Medium.woff2`, the Medium variant of the Fira Sans font in woff2.
+    crate static MEDIUM2: &[u8] = include_bytes!("static/FiraSans-Medium.woff2");
+
     /// The file `FiraSans-LICENSE.txt`, the license text for the Fira Sans font.
     crate static LICENSE: &[u8] = include_bytes!("static/FiraSans-LICENSE.txt");
 }