[css-font-loading] Dictionary arguments must be marked optional.

Author: tabatkins

css-font-loading/Overview.bs

@@ -72,7 +72,7 @@ The <code>FontFace</code> Interface</h2>
 		enum FontFaceLoadStatus { "unloaded", "loading", "loaded", "error" };
 
 		[Constructor(DOMString family, (DOMString or BinaryData) source,
-			         FontFaceDescriptors descriptors),
+			         optional FontFaceDescriptors descriptors),
 		 Exposed=Window,Worker]
 		interface FontFace {
 			attribute DOMString family;

css-font-loading/Overview.html

@@ -196,7 +196,7 @@ <h2 class="heading settled heading" data-level=2 id=fontface-interface><span cla
 enum <dfn class=idl-code data-dfn-type=enum data-export="" data-global-name="" id=enumdef-fontfaceloadstatus>FontFaceLoadStatus<a class=self-link href=#enumdef-fontfaceloadstatus></a></dfn> { "unloaded", "loading", "loaded", "error" };
 
 [Constructor(DOMString <a class=idl-code data-global-name="FontFace<interface>/FontFace()<method>/family<argument>" data-link-for=FontFace/FontFace() data-link-type=argument href=#dom-fontfacefontface-family title=family>family</a>, (DOMString or <a data-link-type=idl href=#typedefdef-binarydata title=binarydata>BinaryData</a>) <a class=idl-code data-global-name="FontFace<interface>/FontFace()<method>/source<argument>" data-link-for=FontFace/FontFace() data-link-type=argument href=#dom-fontfacefontface-source title=source>source</a>,
-           <a data-link-type=idl href=#dictdef-fontfacedescriptors title=fontfacedescriptors>FontFaceDescriptors</a> <a class=idl-code data-global-name="FontFace<interface>/FontFace()<method>/descriptors<argument>" data-link-for=FontFace/FontFace() data-link-type=argument href=#dom-fontfacefontface-descriptors title=descriptors>descriptors</a>),
+           optional <a data-link-type=idl href=#dictdef-fontfacedescriptors title=fontfacedescriptors>FontFaceDescriptors</a> <a class=idl-code data-global-name="FontFace<interface>/FontFace()<method>/descriptors<argument>" data-link-for=FontFace/FontFace() data-link-type=argument href=#dom-fontfacefontface-descriptors title=descriptors>descriptors</a>),
  Exposed=Window,Worker]
 interface <dfn class=idl-code data-dfn-type=interface data-export="" data-global-name="" id=dom-fontface>FontFace<a class=self-link href=#dom-fontface></a></dfn> {
   attribute DOMString <a class=idl-code data-global-name="FontFace<interface>/family<attribute>" data-link-for=FontFace data-link-type=attribute data-type="DOMString " href=#dom-fontface-family title=family>family</a>;