fixed missing abbr closing tag

there was duplicate </a> what should have been a </abbr>.
Also please backport this to 2.1 version

Author: jusurb

src/CodeCoverage/Report/HTML/Renderer/Dashboard.php

@@ -213,7 +213,7 @@ protected function insufficientCoverage(array $classes, $baseLink)
             list($class, $method) = explode('::', $methodName);
 
             $result['method'] .= sprintf(
-                '       <tr><td><a href="%s"><abbr title="%s">%s</a></a></td><td class="text-right">%d%%</td></tr>' . "\n",
+                '       <tr><td><a href="%s"><abbr title="%s">%s</abbr></a></td><td class="text-right">%d%%</td></tr>' . "\n",
                 str_replace($baseLink, '', $classes[$class]['methods'][$method]['link']),
                 $methodName,
                 $method,