[css-grid] Allow empty name sets in <line-names>

Author: fantasai

css-grid/Overview.html

@@ -1318,7 +1318,7 @@ <h3 id=track-sizing><span class=secno>5.1. </span> Track Sizing: the ‘<a
    id=lttrack-breadth>&lt;track-breadth></dfn> = <var>&lt;length></var> | <var>&lt;percentage></var> | <a
    href="#ltflex"><var>&lt;flex></var></a> | min-content | max-content
 <dfn
-   id=ltline-names>&lt;line-names></dfn>    = ( <var>&lt;ident></var>+ )
+   id=ltline-names>&lt;line-names></dfn>    = ( <var>&lt;ident></var>* )
 
 	</pre>
 

css-grid/Overview.src.html

@@ -938,7 +938,7 @@ <h3 id='track-sizing'>
 <dfn>&lt;track-list></dfn>    = [ <var>&lt;line-names></var>? [ <var>&lt;track-size></var> | <var>&lt;repeat-function></var> ] ]+ <var>&lt;line-names></var>?
 <dfn>&lt;track-size></dfn>    = minmax( <var>&lt;track-breadth></var> , <var>&lt;track-breadth></var> ) | auto | <var>&lt;track-breadth></var>
 <dfn>&lt;track-breadth></dfn> = <var>&lt;length></var> | <var>&lt;percentage></var> | <var>&lt;flex></var> | min-content | max-content
-<dfn>&lt;line-names></dfn>    = ( <var>&lt;ident></var>+ )
+<dfn>&lt;line-names></dfn>    = ( <var>&lt;ident></var>* )
 
 	<p>Where:
 
@@ -2920,4 +2920,4 @@ <h2 class="no-num" id="changes">
 		<li>Changed the syntax of <a href="#named-lines">named lines</a> to use parentheses and identifiers rather than strings.
 		<li>Removed the ''none'' value from 'grid-auto-flow', turning auto-placement on by default so that grid items by default don't stack on top of each other.
 		<li>Made named grid areas <a href="#implict-named-lines">imply named grid lines</a>.
-	</ul>
+	</ul>