Update link diffing tests to account for new classes

Author: jschroed91

tests/fixtures/HtmlDiff/issue-28-link-changes.html

@@ -9,7 +9,7 @@
 </newText>
 
 <expected>
-Testing <del class="diffmod diff-href"><a href="http://google.com">Link Changes</a></del><ins class="diffmod diff-href"><a href="http://caxy.com">Link Changes</a></ins>
+Testing <del class="diffmod diffa diffhref"><a href="http://google.com">Link Changes</a></del><ins class="diffmod diffa diffhref"><a href="http://caxy.com">Link Changes</a></ins>
  And when the link <a href="http://samelink.com">stays the same</a>
 </expected>