Merge branch 'skip_to_buttons_on_tab_in_issues_page' into 'master'

Skip to buttons on tabbing in issues page

This will skip tabbing right to "Add comment" or "close" buttons.

http://www.w3.org/TR/html5/editing.html#sequential-focus-navigation-and-the-tabindex-attribute

For tabindex:

```
If the value is a negative integer
The user agent must set the element's tabindex focus flag, but should not allow the element to be reached using sequential focus navigation.
```

app/views/projects/notes/_form.html.haml

@@ -17,8 +17,8 @@
       = f.text_area :note, size: 255, class: 'note_text js-note-text js-gfm-input markdown-area'
 
       .light.clearfix
-        .pull-left Comments are parsed with #{link_to "GitLab Flavored Markdown", help_page_path("markdown", "markdown"), target: '_blank'}
-        .pull-right Attach images (JPG, PNG, GIF) by dragging & dropping or #{link_to "selecting them", '#', class: 'markdown-selector' }.
+        .pull-left Comments are parsed with #{link_to "GitLab Flavored Markdown", help_page_path("markdown", "markdown"),{ target: '_blank', tabindex: -1 }}
+        .pull-right Attach images (JPG, PNG, GIF) by dragging & dropping or #{link_to "selecting them", '#', class: 'markdown-selector', tabindex: -1 }.
 
     .note-preview-holder.hide
       .js-note-preview