Remove font-display settings

src/librustdoc/html/static/rustdoc.css

@@ -3,14 +3,12 @@
 	font-family: 'Fira Sans';
 	font-style: normal;
 	font-weight: 400;
-	font-display: optional;
 	src: local('Fira Sans'), url("FiraSans-Regular.woff") format('woff');
 }
 @font-face {
 	font-family: 'Fira Sans';
 	font-style: normal;
 	font-weight: 500;
-	font-display: optional;
 	src: local('Fira Sans Medium'), url("FiraSans-Medium.woff") format('woff');
 }
 
@@ -19,23 +17,18 @@
 	font-family: 'Source Serif Pro';
 	font-style: normal;
 	font-weight: 400;
-	/* The difference for body text without this font is greater than other fonts,
-	 * so the 0~100ms block of fallback is preferred over optional, for legibility. */
-	font-display: fallback;
 	src: local('Source Serif Pro'), url("SourceSerifPro-Regular.ttf.woff") format('woff');
 }
 @font-face {
 	font-family: 'Source Serif Pro';
 	font-style: italic;
 	font-weight: 400;
-	font-display: optional;
 	src: local('Source Serif Pro Italic'), url("SourceSerifPro-It.ttf.woff") format('woff');
 }
 @font-face {
 	font-family: 'Source Serif Pro';
 	font-style: normal;
 	font-weight: 700;
-	font-display: optional;
 	src: local('Source Serif Pro Bold'), url("SourceSerifPro-Bold.ttf.woff") format('woff');
 }
 
@@ -44,7 +37,6 @@
 	font-family: 'Source Code Pro';
 	font-style: normal;
 	font-weight: 400;
-	font-display: optional;
 	/* Avoid using locally installed font because bad versions are in circulation:
 	 * see https://github.com/rust-lang/rust/issues/24355 */
 	src: url("SourceCodePro-Regular.woff") format('woff');
@@ -53,7 +45,6 @@
 	font-family: 'Source Code Pro';
 	font-style: normal;
 	font-weight: 600;
-	font-display: optional;
 	src: url("SourceCodePro-Semibold.woff") format('woff');
 }