Merge branch 'bpj-merge-request-diff-fixes' into 'master'

Fixups for Frontend for Merge Request Diff

## What does this MR do?

Makes a few revisions to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6343, as per feedback from @DouweM. Specifically, it removes a duplicate in the changelog, removes colons in dropdowns, uses icon helper, and fixes the 'Show original' link path.

## Why was this MR needed?

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6343 was already merged and this is a needed patch. 

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6343

See merge request !6448

CHANGELOG

@@ -178,7 +178,6 @@ v 8.12.0
   - Fix Gitlab::Popen.popen thread-safety issue
   - Add specs to removing project (Katarzyna Kobierska Ula Budziszewska)
   - Clean environment variables when running git hooks
-  - Add UX improvements for merge request version diffs
   - Fix Import/Export issues importing protected branches and some specific models
   - Fix non-master branch readme display in tree view
   - Add UX improvements for merge request version diffs

app/views/discussions/_jump_to_next.html.haml

-- diff_notes_disabled = (@merge_request_diff.latest? && !!@start_sha) if @merge_request_diff
 - discussion = local_assigns.fetch(:discussion, nil)
 - if current_user
   %jump-to-discussion{ "inline-template" => true, ":discussion-id" => "'#{discussion.try(:id)}'" }
@@ -6,6 +5,5 @@
       %button.btn.btn-default.discussion-next-btn.has-tooltip{ "@click" => "jumpToNextUnresolvedDiscussion",
         title: "Jump to next unresolved discussion",
         "aria-label" => "Jump to next unresolved discussion",
-        data: { container: "body" },
-        disabled: diff_notes_disabled }
+        data: { container: "body" }}
         = custom_icon("next_discussion")

app/views/projects/merge_requests/show/_versions.html.haml

@@ -12,9 +12,9 @@
           %span.caret
         %ul.dropdown-menu.dropdown-menu-selectable
           .dropdown-title
-            %span Version:
+            %span Version
             %button.dropdown-title-button.dropdown-menu-close
-              %i.fa.fa-times.dropdown-menu-close-icon
+              = icon('times', class: 'dropdown-menu-close-icon')
           - @merge_request_diffs.each do |merge_request_diff|
             %li
               = link_to merge_request_version_path(@project, @merge_request, merge_request_diff), class: ('is-active' if merge_request_diff == @merge_request_diff) do
@@ -40,9 +40,9 @@
             %span.caret
           %ul.dropdown-menu.dropdown-menu-selectable
             .dropdown-title
-              %span Compared with:
+              %span Compared with
               %button.dropdown-title-button.dropdown-menu-close
-                %i.fa.fa-times.dropdown-menu-close-icon
+                = icon('times', class: 'dropdown-menu-close-icon')
             - @comparable_diffs.each do |merge_request_diff|
               %li
                 = link_to merge_request_version_path(@project, @merge_request, @merge_request_diff, merge_request_diff.head_commit_sha), class: ('is-active' if merge_request_diff == @start_version) do
@@ -67,4 +67,4 @@
           Comments are disabled because you're comparing two versions of this merge request.
         - else
           Comments are disabled because you're viewing an old version of this merge request.
-        = link_to 'Show latest version', merge_request_version_path(@project, @merge_request, @merge_request_diff), class: 'btn btn-sm'
+        = link_to 'Show latest version', diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), class: 'btn btn-sm'