Merge branch 'diff-line-highlighting-fix' into 'master'

Fix line diff side-by-side line highlighting

## What does this MR do?

Fixes line highlighting in diff side-by-side view from working correctly.

The JS was looking for a class, but the class doesn't exist & instead it was a data attribute.

## Screenshots (if relevant)

![Screen_Shot_2016-09-13_at_10.26.15](/uploads/7aca730efb14d7bd6bad2a8712fe39d2/Screen_Shot_2016-09-13_at_10.26.15.png)

See merge request !6316

app/assets/javascripts/merge_request_tabs.js

@@ -232,10 +232,10 @@
       $('.hll').removeClass('hll');
       locationHash = window.location.hash;
       if (locationHash !== '') {
-        hashClassString = "." + (locationHash.replace('#', ''));
+        dataLineString = '[data-line-code="' + locationHash.replace('#', '') + '"]';
         $diffLine = $(locationHash + ":not(.match)", $('#diffs'));
         if (!$diffLine.is('tr')) {
-          $diffLine = $('#diffs').find("td" + locationHash + ", td" + hashClassString);
+          $diffLine = $('#diffs').find("td" + locationHash + ", td" + dataLineString);
         } else {
           $diffLine = $diffLine.find('td');
         }