[css-font-loading] Fix FontFaceLoadEventInit default value.

Author: tabatkins

css-font-loading/Overview.bs

@@ -335,7 +335,7 @@ The <code>FontFaceSet</code> Interface</h2>
 
 	<pre class="idl">
 		dictionary CSSFontFaceLoadEventInit : EventInit {
-			sequence&lt;CSSFontFaceRule> fontfaces = null;
+			sequence&lt;CSSFontFaceRule> fontfaces = [];
 		};
 
 		[Constructor(DOMString type, optional CSSFontFaceLoadEventInit eventInitDict)]

css-font-loading/Overview.html

@@ -434,7 +434,7 @@ <h2 class="heading settled heading" data-level=3 id=FontFaceSet-interface><span
 The <code>FontFaceSet</code> Interface</span><a class=self-link href=#FontFaceSet-interface></a></h2>
 
 	<pre class=idl>dictionary <dfn class=idl-code data-dfn-type=dictionary data-export="" data-global-name="" id=dictdef-cssfontfaceloadeventinit>CSSFontFaceLoadEventInit<a class=self-link href=#dictdef-cssfontfaceloadeventinit></a></dfn> : <a data-link-type=idl href=http://dom.spec.whatwg.org/#eventinit title=eventinit>EventInit</a> {
-  sequence&lt;<a data-link-type=idl title=cssfontfacerule>CSSFontFaceRule</a>&gt; <dfn class=idl-code data-dfn-for=CSSFontFaceLoadEventInit data-dfn-type=dict-member data-export="" data-global-name="CSSFontFaceLoadEventInit<dictionary>/fontfaces<dict-member>" id=dom-cssfontfaceloadeventinit-fontfaces>fontfaces<a class=self-link href=#dom-cssfontfaceloadeventinit-fontfaces></a></dfn> = null;
+  sequence&lt;<a data-link-type=idl title=cssfontfacerule>CSSFontFaceRule</a>&gt; <dfn class=idl-code data-dfn-for=CSSFontFaceLoadEventInit data-dfn-type=dict-member data-export="" data-global-name="CSSFontFaceLoadEventInit<dictionary>/fontfaces<dict-member>" id=dom-cssfontfaceloadeventinit-fontfaces>fontfaces<a class=self-link href=#dom-cssfontfaceloadeventinit-fontfaces></a></dfn> = [];
 };
 
 [Constructor(DOMString <dfn class=idl-code data-dfn-for=CSSFontFaceLoadEvent/CSSFontFaceLoadEvent() data-dfn-type=argument data-export="" data-global-name="CSSFontFaceLoadEvent<interface>/CSSFontFaceLoadEvent()<method>/type<argument>" id=dom-cssfontfaceloadeventcssfontfaceloadevent-type>type<a class=self-link href=#dom-cssfontfaceloadeventcssfontfaceloadevent-type></a></dfn>, optional <a data-link-type=idl href=#dictdef-cssfontfaceloadeventinit title=cssfontfaceloadeventinit>CSSFontFaceLoadEventInit</a> <dfn class=idl-code data-dfn-for=CSSFontFaceLoadEvent/CSSFontFaceLoadEvent() data-dfn-type=argument data-export="" data-global-name="CSSFontFaceLoadEvent<interface>/CSSFontFaceLoadEvent()<method>/eventinitdict<argument>" id=dom-cssfontfaceloadeventcssfontfaceloadevent-eventinitdict>eventInitDict<a class=self-link href=#dom-cssfontfaceloadeventcssfontfaceloadevent-eventinitdict></a></dfn>)]