Merge branch 'bugfix/jschatz/sidebar-issues/minimize-on-diff' into 'master'

Shrink on diff view

* Shrinks when navigating to diff view.
* Shrinks when refreshing on diff view.
* Expandable at anytime.

![diff](/uploads/ec3ff1e7be7571a3af251e9ec9f704c1/diff.gif)


See merge request !2735

app/assets/javascripts/merge_request_tabs.js.coffee

@@ -70,6 +70,7 @@ class @MergeRequestTabs
       @loadCommits($target.attr('href'))
     else if action == 'diffs'
       @loadDiff($target.attr('href'))
+      @shrinkView()
     else if action == 'builds'
       @loadBuilds($target.attr('href'))
 
@@ -185,3 +186,14 @@ class @MergeRequestTabs
 
   expandViewContainer: ->
     $('.container-fluid').removeClass('container-limited')
+
+  shrinkView: ->
+    $gutterIcon = $('.gutter-toggle i')
+
+    # Wait until listeners are set
+    setTimeout( ->
+      # Only when sidebar is collapsed
+      if $gutterIcon.is('.fa-angle-double-right')
+        $gutterIcon.closest('a').trigger('click')
+    , 0)
+