[css-font-loading-3][editorial] Reference WebIDL BufferSource

Rather than defining a custom BinaryData typedef, the FontSource
interface should just use the BufferSource definition from WebIDL.

https://webidl.spec.whatwg.org/#BufferSource

Author: ADKaster

css-font-loading-3/Overview.bs

@@ -77,7 +77,7 @@ The <code>FontFace</code> Interface</h2>
 
 	The {{FontFace}} interface represents a single usable font face.
 	CSS ''@font-face'' rules implicitly define FontFace objects,
-	or they can be constructed manually from a url or binary data.
+	or they can be constructed manually from a url or a buffer source.
 
 	<xmp class="idl">
 		dictionary FontFaceDescriptors {
@@ -208,7 +208,7 @@ The Constructor</h3>
 
 	A {{FontFace}} can be constructed either
 	from a URL pointing to a font face file,
-	or from an {{ArrayBuffer}} (or {{ArrayBufferView}}) containing the binary representation of a font face.
+	or from a {{BufferSource}} containing the binary representation of a font face.
 
 	When the <dfn constructor for=FontFace>FontFace(family, source, descriptors)</dfn> method is called,
 	execute these steps:
@@ -315,7 +315,7 @@ The <code>load()</code> method</h3>
 
 	The {{FontFace/load()}} method of {{FontFace}}
 	forces a url-based font face to request its font data and load.
-	For fonts constructed from binary data,
+	For fonts constructed from a buffer source,
 	or fonts that are already loading or loaded,
 	it does nothing.