Polish on typo subs

examples/article.html

@@ -18,6 +18,9 @@
   <h2>A description of the article</h2>
   <dt-byline></dt-byline>
   <p>This is the first paragraph of the article.</p>
+  <p>Test a long&thinsp;&mdash;&thinsp;dash -- here it is.</p>
+  <p>Test for owner's possessive.</p>
+  <p>Test for "quoting a passage." And another sentence. Or two.</p>
   <p>We can also cite <dt-cite key="gregor2015draw,mercier2011humans"></dt-cite> external publications. <dt-cite key="dong2014image,dumoulin2016guide,mordvintsev2015inceptionism"></dt-cite></p>
 </dt-article>