Add test for recent XHTML regression

Author: dwarring

t/tag-set-xhtml.t

@@ -14,6 +14,10 @@ is $tag-set.tag-style('small'), 'font-size:0.83em;';
 $tag-set.base-style('small').font-size = '0.75em';
 is $tag-set.tag-style('small'), 'font-size:0.75em;';
 
+is $tag-set.tag-style('p'), 'display:block; margin-bottom:1.12em; margin-top:1.12em; unicode-bidi:embed;';
+my $hidden = '';
+is $tag-set.tag-style('p', :$hidden), 'display:none; margin-bottom:1.12em; margin-top:1.12em; unicode-bidi:embed;';
+
 $tag-set.base-style('blah').font-weight = 'bold';
 is $tag-set.tag-style('blah'), 'font-weight:bold;';