Merge branch '23866-builds-dropdown' into 'master'

Increase z index on fixed mr tabs

Before:
<img src="/uploads/e890a4f185af87b66251d744fbe840d5/Screen_Shot_2016-10-26_at_11.58.45_AM.png" width="400px">

After:
<img src="/uploads/0bbf72888f6a47bd3027ee7dfff542da/Screen_Shot_2016-10-26_at_11.58.28_AM.png" width="400px">
Closes #23866

See merge request !7124
Signed-off-by: Rémy Coutable <remy@rymai.me>

app/assets/stylesheets/pages/merge_requests.scss

@@ -439,12 +439,12 @@
 }
 
 .merge-request-tabs-holder {
-  background-color: #fff;
+  background-color: $white-light;
 
   &.affix {
     top: 100px;
     left: 0;
-    z-index: 9;
+    z-index: 10;
     transition: right .15s;
   }