Make tab target selectors less naive

Prior, any of the specified IDs could have been hijacked by a table of
contents header, breaking the tab functionality. For example, a `##
Notes` header would get the id `notes` and prevent the Discussion tab
from being activated.

Closes #3908

app/views/projects/merge_requests/_new_submit.html.haml

@@ -20,11 +20,11 @@
 .mr-compare.merge-request
   %ul.merge-request-tabs.center-top-menu.no-top.no-bottom
     %li.commits-tab
-      = link_to url_for(params), data: {target: '#commits', action: 'commits', toggle: 'tab'} do
+      = link_to url_for(params), data: {target: 'div#commits', action: 'commits', toggle: 'tab'} do
         Commits
         %span.badge= @commits.size
     %li.diffs-tab.active
-      = link_to url_for(params), data: {target: '#diffs', action: 'diffs', toggle: 'tab'} do
+      = link_to url_for(params), data: {target: 'div#diffs', action: 'diffs', toggle: 'tab'} do
         Changes
         %span.badge= @diffs.size
 

app/views/projects/merge_requests/_show.html.haml

@@ -44,15 +44,15 @@
   - if @commits.present?
     %ul.merge-request-tabs.center-top-menu.no-top.no-bottom
       %li.notes-tab
-        = link_to namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: {target: '#notes', action: 'notes', toggle: 'tab'} do
+        = link_to namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: {target: 'div#notes', action: 'notes', toggle: 'tab'} do
           Discussion
           %span.badge= @merge_request.mr_and_commit_notes.user.count
       %li.commits-tab
-        = link_to commits_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: {target: '#commits', action: 'commits', toggle: 'tab'} do
+        = link_to commits_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: {target: 'div#commits', action: 'commits', toggle: 'tab'} do
           Commits
           %span.badge= @commits.size
       %li.diffs-tab
-        = link_to diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: {target: '#diffs', action: 'diffs', toggle: 'tab'} do
+        = link_to diffs_namespace_project_merge_request_path(@project.namespace, @project, @merge_request), data: {target: 'div#diffs', action: 'diffs', toggle: 'tab'} do
           Changes
           %span.badge= @merge_request.diffs.size
 

spec/javascripts/fixtures/merge_request_tabs.html.haml

 %ul.nav.nav-tabs.merge-request-tabs
   %li.notes-tab
-    %a{href: '/foo/bar/merge_requests/1', data: {target: '#notes', action: 'notes', toggle: 'tab'}}
+    %a{href: '/foo/bar/merge_requests/1', data: {target: 'div#notes', action: 'notes', toggle: 'tab'}}
       Discussion
   %li.commits-tab
-    %a{href: '/foo/bar/merge_requests/1/commits', data: {target: '#commits', action: 'commits', toggle: 'tab'}}
+    %a{href: '/foo/bar/merge_requests/1/commits', data: {target: 'div#commits', action: 'commits', toggle: 'tab'}}
       Commits
   %li.diffs-tab
-    %a{href: '/foo/bar/merge_requests/1/diffs', data: {target: '#diffs', action: 'diffs', toggle: 'tab'}}
+    %a{href: '/foo/bar/merge_requests/1/diffs', data: {target: 'div#diffs', action: 'diffs', toggle: 'tab'}}
       Diffs
 
 .tab-content