[css-font-loading-3] Remove unused ForEachCallback (#5785)

* [font-loading-3] Remove unused ForEachCallback

* Reuse BufferSource

css-font-loading-3/Overview.bs

@@ -80,8 +80,6 @@ The <code>FontFace</code> Interface</h2>
 	or they can be constructed manually from a url or binary data.
 
 	<xmp class="idl">
-		typedef (ArrayBuffer or ArrayBufferView) BinaryData;
-
 		dictionary FontFaceDescriptors {
 			CSSOMString style = "normal";
 			CSSOMString weight = "normal";
@@ -99,7 +97,7 @@ The <code>FontFace</code> Interface</h2>
 
 		[Exposed=(Window,Worker)]
 		interface FontFace {
-			constructor(CSSOMString family, (CSSOMString or BinaryData) source,
+			constructor(CSSOMString family, (CSSOMString or BufferSource) source,
 		                optional FontFaceDescriptors descriptors = {});
 			attribute CSSOMString family;
 			attribute CSSOMString style;
@@ -255,7 +253,7 @@ The Constructor</h3>
 	2. If the {{source!!argument}} argument was a {{CSSOMString}},
 		set <var>font face's</var> internal {{[[Urls]]}} slot to the string.
 
-		If the {{source}} argument was a {{BinaryData}},
+		If the {{source}} argument was a {{BufferSource}},
 		set <var>font face's</var> internal {{[[Data]]}} slot to the passed argument.
 
 	3. If <var>font face's</var> {{[[Data]]}} slot is not <code>null</code>,