Fixed merge request changes sticky container not spreading full width

app/assets/stylesheets/pages/issuable.scss

@@ -35,7 +35,7 @@
   .commit-box,
   .info-well,
   .commit-ci-menu,
-  .files-changed,
+  .files-changed-inner,
   .limited-header-width,
   .limited-width-notes {
     @extend .fixed-width-container;

app/views/projects/diffs/_diffs.html.haml

@@ -4,6 +4,7 @@
 - diff_files = diffs.diff_files
 
 .content-block.oneline-block.files-changed.diff-files-changed.js-diff-files-changed
+  .files-changed-inner
     .inline-parallel-buttons
       - if !diffs_expanded? && diff_files.any? { |diff_file| diff_file.collapsed? }
         = link_to 'Expand all', url_for(params.merge(expanded: 1, format: nil)), class: 'btn btn-default'