Auto merge of #16224 - servo:valid-fontface, r=upsuper

Make the parser accept @font-face rules without font-family or src.

Fix #16165.

Also, it turns out that the CSSFontFaceRule IDL specified in the css-fonts spec is not web-compatible. Instead browsers implement a .style attribute like in CSSStyleRule: https://github.com/w3c/csswg-drafts/issues/825

This in turn requires preserving data about which descriptors were set or not (distinguishing unset from set to a value that happens to be the initial value), so this commit also makes every field `Option<_>`.

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1 files changed, 6 insertions, 9 deletions

diff --git a/components/script/dom/webidls/CSSFontFaceRule.webidl b/components/script/dom/webidls/CSSFontFaceRule.webidl
index 3749a79a818..a0a1b8f950b 100644
--- a/components/script/dom/webidls/CSSFontFaceRule.webidl
+++ b/components/script/dom/webidls/CSSFontFaceRule.webidl
@@ -2,16 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-// https://drafts.csswg.org/css-fonts/#cssfontfacerule
+// https://drafts.csswg.org/css-fonts/#cssfontfacerule is unfortunately not web-compatible:
+// https://github.com/w3c/csswg-drafts/issues/825
+
+// https://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/css.html#CSS-CSSFontFaceRule ,
+// plus extended attributes matching CSSStyleRule
 [Exposed=Window]
 interface CSSFontFaceRule : CSSRule {
-  // attribute DOMString family;
-  // attribute DOMString src;
-  // attribute DOMString style;
-  // attribute DOMString weight;
-  // attribute DOMString stretch;
-  // attribute DOMString unicodeRange;
-  // attribute DOMString variant;
-  // attribute DOMString featureSettings;
+  // [SameObject, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
 };