monoblue: also highlight target line on annotate and comparison pages

Clicking on a line link on pages that show any kind of file contents (including
diffs) should highlight that line, and in monoblue it works when there's a
<pre> element (e.g. diff), but pages that use <table> element (annotate and
compare) need this css class. It matches and highlights linked (":target")
table rows. This line is pretty much copied from gitweb theme.

mercurial/templates/static/style-monoblue.css

@@ -321,6 +321,7 pre.sourcelines.stripes > :nth-child(4n+
 pre.sourcelines.stripes > :nth-child(4n+1):hover + :nth-child(4n+2),
 pre.sourcelines.stripes > :nth-child(4n+3):hover + :nth-child(4n+4) { background-color: #D5E1E6; }
 
+tr:target td,
 pre.sourcelines > span:target,
 pre.sourcelines.stripes > span:target {
     background-color: #bfdfff;