Fix typo (#1635)

sections/semantics-links.include

@@ -720,7 +720,7 @@
     the <code>target</code> attribute as the browsing context name. If
     these rules result in the creation of a new <a>browsing context</a>, set <var>replace</var> to true.
 
-    Otherwise, if <var>target</var> is an <{a}> or <{area}> element
+    Otherwise, if <var>subject</var> is an <{a}> or <{area}> element
     with no <code>target</code> attribute, but the
     {{Document}} contains a <{base}> element with a <code>target</code> attribute, then let <var>target</var> be the
     <a>browsing context</a> that is chosen by applying <a>the rules for choosing a browsing