[css-font-loading] Use the same error for parsing descriptors in constructor and later.

Author: tabatkins

css-font-loading/Overview.bs

@@ -111,7 +111,7 @@ The <code>FontFace</code> Interface</h2>
 
 			On setting, parse the string according to the grammar for the CSS ''@font-face'' rule.
 			If it does not match the grammar,
-			throw a TypeError;
+			throw a SyntaxError;
 			otherwise, set the attribute to the provided string.
 
 		<dt><dfn>variant</dfn>, <span attribute-info for=variant></span>
@@ -129,7 +129,7 @@ The <code>FontFace</code> Interface</h2>
 
 			On setting, parse the string according to the grammar for the CSS ''@font-face'' rule.
 			If it does not match the grammar,
-			throw a TypeError;
+			throw a SyntaxError;
 			otherwise, set the attribute to the provided string.
 
 		<dt><dfn>status</dfn>, <span attribute-info for=FontFace/status></span>

css-font-loading/Overview.html

@@ -247,7 +247,7 @@ <h2 class="heading settled heading" data-level=2 id=fontface-interface><span cla
 
 <p>On setting, parse the string according to the grammar for the CSS <a class=css data-link-type=maybe href=http://dev.w3.org/csswg/css-fonts-3/#at-font-face-rule title=@font-face>@font-face</a> rule.
 			If it does not match the grammar,
-			throw a TypeError;
+			throw a SyntaxError;
 			otherwise, set the attribute to the provided string.</p>
 
 		<dt><dfn class=idl-code data-dfn-for=FontFace data-dfn-type=attribute data-export="" id=dom-fontface-variant>variant<a class=self-link href=#dom-fontface-variant></a></dfn>, <span data-attribute-info="" for=variant> of type <a data-link-type=idl-name title=domstring>DOMString</a></span>
@@ -265,7 +265,7 @@ <h2 class="heading settled heading" data-level=2 id=fontface-interface><span cla
 
 <p>On setting, parse the string according to the grammar for the CSS <a class=css data-link-type=maybe href=http://dev.w3.org/csswg/css-fonts-3/#at-font-face-rule title=@font-face>@font-face</a> rule.
 			If it does not match the grammar,
-			throw a TypeError;
+			throw a SyntaxError;
 			otherwise, set the attribute to the provided string.</p>
 
 		<dt><dfn class=idl-code data-dfn-for=FontFace data-dfn-type=attribute data-export="" id=dom-fontface-status>status<a class=self-link href=#dom-fontface-status></a></dfn>, <span data-attribute-info="" for=FontFace/status> of type <a data-link-type=idl-name href=#enumdef-fontfaceloadstatus title=fontfaceloadstatus>FontFaceLoadStatus</a>, readonly</span>