Fix selflink styles

Selflinks should inherit color and text-decoration styles, and
be bolded. This matches how they are displayed in other skins,
and how they were displayed before a change to mediawiki core
in MW-1.29 ( If058843924c3b30c116df2520aef93a004d98a5d ).

Bug: T192033
Change-Id: Id61f06a6b1921208d5436cb6e21f710413e990e9

resources/screen-common.less

@@ -266,6 +266,11 @@ a.new,
 		color: @red-dark;
 	}
 }
+a.mw-selflink {
+	color: inherit;
+	font-weight: bold;
+	text-decoration: inherit;
+}
 
 .mw-editsection {
 	font-family: @fonts;