[selectors-4] Add back definition for the (non-functional-notation) :local-link pseudo-class, adjust to account for fragment identifiers. Closes w3c#2010.

Author: fantasai

selectors-4/Overview.bs

@@ -237,14 +237,19 @@ Selectors Overview</h2>
 						of which the target is already visited
 				<td>[[#link]]
 				<td>1
+			<tr>
+				<td><code>E:local-link</code>
+				<td>an E element being the source anchor of a hyperlink
+					targetting the current URL
+				<td>[[#the-local-link-pseudo]]
 			<tr>
 				<td><code>E:target</code>
-				<td>an E element being the target of the referring URL
+				<td>an E element being the target of the current URL
 				<td>[[#the-target-pseudo]]
 				<td>3
 			<tr>
 				<td><code>E:target-within</code>
-				<td>an E element that is the target of the referring URL or contains an element that does.
+				<td>an E element that is the target of the current URL or contains an element that does.
 				<td>[[#the-target-within-pseudo]]
 				<td>4
 			<tr>
@@ -1976,6 +1981,39 @@ The Link History Pseudo-classes: '':link'' and '':visited''</h3>
 	or implement other measures to preserve the user's privacy
 	while rendering visited and unvisited links differently.
 
+<h3 id="the-local-link-pseudo">
+The Local Link Pseudo-class: '':local-link''</h3>
+
+	The <dfn id='local-link-pseudo'>:local-link</dfn> pseudo-class
+	allows authors to style <a href="#the-any-link-pseudo">hyperlinks</a>
+	based on the users current location within a site.
+	It represents an element that is
+	the source anchor of a hyperlink whose target's absolute URL
+	matches the element's own document URL.
+	If the hyperlink's target includes a fragment URL,
+	then the fragment URL of the current URL must also match;
+	if it does not, then the fragment URL portion of the current URL
+	is not taken into account in the comparison.
+
+	<div class="example">
+		For example, the following rule prevents links targetting the
+		current page from being underlined when they are part of the
+		navigation list:
+
+		<pre>nav :local-link { text-decoration: none; } </pre>
+	</div>
+
+	Note: The current URL of a page can change as a result of user actions
+	such as activating a link targetting a different fragment within the same page;
+	or by use of the <code>pushState</code> API;
+	as well as by the more obvious actions of navigating to a different page
+	or following a redirect (which could be initiated by protocols such as HTTP,
+	markup instructions such as <code>&lt;meta http-equiv="..."></code>,
+	or scripting instructions <!-- such as ? -->).
+	UAs must ensure that '':local-link'',
+	as well as the '':target'' and '':target-within'' pseudo-classes below,
+	respond correctly to all such changes in state.
+
 <h3 id="the-target-pseudo">
 The Target Pseudo-class: '':target''</h3>
 
@@ -3748,8 +3786,10 @@ Changes</h2>
 
 			Issue: Do we have implementations of this? If not, maybe it's better to keep the restriction for level 4?
 		<li>Defined <a>specificity</a> of a <a>selector list</a>. (Why?)
-		<li>Required quotes around '':lang()'' values involving an asterisk.
-		<li>Removed the <css>:local-link</css> and reference combinator for lack of interest.
+		<li>Required quotes around '':lang()'' values involving an asterisk;
+			only language codes which happen to bhe CSS identifiers can be used unquoted.
+		<li>Changed the <css>:local-link</css> pseudo-class to account for fragment URLs.
+		<li>Removed the <code>:local-link()</code> pseudo-class and reference combinator for lack of interest.
 	</ul>