[selectors] Add example of :matches() specificity. Also, typo.

Author: tabatkins

selectors/Overview.html

@@ -4224,10 +4224,18 @@ <h2 id=specificity><span class=secno>15. </span> Calculating a selector's
 <!--
     -->#x34y           /* a=1 b=0 c=0 */
 <!--
-    -->#s12:not(FOO)   /* a=1 b=0 c=1 */</pre>
+    -->#s12:not(FOO)   /* a=1 b=0 c=1 */
+<!--
+    -->.foo :matches(.bar, #baz)
+<!--
+    -->                /* Either a=1 b=1 c=0
+<!--
+    -->                   or a=0 b=2 c=0, depending
+<!--
+    -->                   on the element being matched. */</pre>
   </div>
 
-  <p class=note><strong>Note:</strong> Repeated occurrances of the same
+  <p class=note><strong>Note:</strong> Repeated occurrences of the same
    simple selector are allowed and do increase specificity.
 
   <p class=note><strong>Note:</strong> The specificity of the styles

selectors/Overview.src.html

@@ -3052,10 +3052,15 @@ <h2 id="specificity">
     -->UL OL LI.red    /* a=0 b=1 c=3 */&#xa;<!--
     -->LI.red.level    /* a=0 b=2 c=1 */&#xa;<!--
     -->#x34y           /* a=1 b=0 c=0 */&#xa;<!--
-    -->#s12:not(FOO)   /* a=1 b=0 c=1 */</pre>
+    -->#s12:not(FOO)   /* a=1 b=0 c=1 */&#xa;<!--
+    -->.foo :matches(.bar, #baz)&#xa;<!--
+    -->                /* Either a=1 b=1 c=0&#xa;<!--
+    -->                   or a=0 b=2 c=0, depending&#xa;<!--
+    -->                   on the element being matched. */</pre>
+
   </div>
 
-  <p class="note"><strong>Note:</strong> Repeated occurrances of the
+  <p class="note"><strong>Note:</strong> Repeated occurrences of the
   same simple selector are allowed and do increase specificity.
 
   <p class="note"><strong>Note:</strong> The specificity of the styles