IE11: Permalink "Edit" and "Ok" buttons have improper padding.

[kjellr]

Describe the bug

When using Gutenberg with IE11, the permalink settings buttons have incorrect padding:

The "Edit" button appears with no right padding:

The "OK" button appears with unequal padding on either side:

To Reproduce

1. Use IE11
2. Add a title, save your post.
3. Click the title.
4. Take note of the button padding as described above.

(Note that your permalink structure must include %postname% or %pagename% in order to get these options)

Tested in
Windows 7, IE 11.0.9600.17420
Gutenberg 3.4

[kjellr]

Closing in favor of #7481