Apply gitlab button style to buttons in app/views/discussions directory

app/views/discussions/_diff_with_notes.html.haml

@@ -29,7 +29,7 @@
             %td.line_content.js-success-lazy-load
               .js-code-placeholder
             %td.js-error-lazy-load-diff.hidden.diff-loading-error-block
-              - button = button_tag(_("Try again"), class: "btn-link btn-link-retry btn-no-padding js-toggle-lazy-diff-retry-button")
+              - button = button_tag(_("Try again"), class: "btn-link gl-button btn-link-retry btn-no-padding js-toggle-lazy-diff-retry-button")
               = _("Unable to load the diff. %{button_try_again}").html_safe % { button_try_again: button}
           = render "discussions/diff_discussion", discussions: [discussion], expanded: true
   - else

app/views/discussions/_jump_to_next.html.haml

@@ -2,7 +2,7 @@
 - if current_user
   %jump-to-discussion{ "inline-template" => true, ":discussion-id" => "'#{discussion.try(:id)}'" }
     .btn-group{ role: "group", "v-show" => "!allResolved", "v-if" => "showButton" }
-      %button.btn.btn-default.discussion-next-btn.has-tooltip{ "@click" => "jumpToNextUnresolvedDiscussion",
+      %button.btn.gl-button.btn-default.discussion-next-btn.has-tooltip{ "@click" => "jumpToNextUnresolvedDiscussion",
         ":title" => "buttonText",
         ":aria-label" => "buttonText",
         data: { container: "body" } }

app/views/discussions/_new_issue_for_all_discussions.html.haml

@@ -5,4 +5,4 @@
               title: 'Resolve all discussions in new issue',
               aria: { label: 'Resolve all discussions in new issue' },
               data: { container: 'body' },
-              class: 'new-issue-for-discussion btn btn-default discussion-create-issue-btn has-tooltip'
+              class: 'new-issue-for-discussion btn gl-button btn-default discussion-create-issue-btn has-tooltip'

app/views/discussions/_new_issue_for_discussion.html.haml

@@ -7,4 +7,4 @@
                 title: 'Resolve this thread in a new issue',
                 aria: { label: 'Resolve this thread in a new issue' },
                 data: { container: 'body' },
-                class: 'new-issue-for-discussion btn btn-default discussion-create-issue-btn has-tooltip'
+                class: 'new-issue-for-discussion btn gl-button btn-default discussion-create-issue-btn has-tooltip'

app/views/discussions/_notes.html.haml

@@ -9,9 +9,9 @@
   -# to the first note position when we click on a badge diff discussion
   %ul.notes{ id: "discussion_#{discussion.id}", data: { discussion_id: discussion.id, position: discussion.notes[0].position.to_json } }
     - if discussion.try(:on_image?) && show_toggle
-      %button.diff-notes-collapse.js-diff-notes-toggle{ type: 'button' }
+      %button.gl-button.diff-notes-collapse.js-diff-notes-toggle{ type: 'button' }
         = sprite_icon('collapse', css_class: 'collapse-icon')
-      %button.btn-transparent.badge.badge-pill.js-diff-notes-toggle{ type: 'button' }
+      %button.gl-button.btn-transparent.badge.badge-pill.js-diff-notes-toggle{ type: 'button' }
         = badge_counter
     = render partial: "shared/notes/note", collection: discussion.notes, as: :note, locals: { badge_counter: badge_counter, show_image_comment_badge: show_image_comment_badge }