gitweb: make span.age CSS selector more specific

This set of CSS properties is only used on /changelog page to make age elements
float to the left and be fixed in size, but span.a is too broad of a selector,
because we don't want to apply these properties to all <span> elements that
have age class.

mercurial/templates/static/style-gitweb.css

@@ -29,7 +29,7 b' a.title:hover { background-color: #d9d8d'
 div.title_text { padding:6px 0px; border: solid #d9d8d1; border-width:0px 0px 1px; }
 div.log_body { padding:8px 8px 8px 150px; }
 .age { white-space:nowrap; }
-span.age { position:relative; float:left; width:142px; font-style:italic; }
+a.title span.age { position:relative; float:left; width:142px; font-style:italic; }
 div.log_link {
 	padding:0px 8px;
 	font-size:10px; font-family:sans-serif; font-style:normal;

tests/test-hgweb.t

@@ -340,7 +340,7 b' static file'
 
   $ get-with-headers.py --twice localhost:$HGPORT 'static/style-gitweb.css' - date etag server
   200 Script output follows
-  content-length: 9118
+  content-length: 9126
   content-type: text/css
   
   body { font-family: sans-serif; font-size: 12px; border:solid #d9d8d1; border-width:1px; margin:10px; background: white; color: black; }
@@ -374,7 +374,7 b' static file'
   div.title_text { padding:6px 0px; border: solid #d9d8d1; border-width:0px 0px 1px; }
   div.log_body { padding:8px 8px 8px 150px; }
   .age { white-space:nowrap; }
-  span.age { position:relative; float:left; width:142px; font-style:italic; }
+  a.title span.age { position:relative; float:left; width:142px; font-style:italic; }
   div.log_link {
   	padding:0px 8px;
   	font-size:10px; font-family:sans-serif; font-style:normal;