Fix permission cornerstone when few permissions selected
Fix permission cornerstone when few permissions selected

Test Plan:
  * Compile css
  * Go to new permissions page
  * Filter down to 1 role
  * Make sure the 'permissions' cornerstone doesn't expand to take up
    more of the page

Change-Id: I065bd36220c20408895a2dbf65872acc7eea0e28
Reviewed-on: https://gerrit.instructure.com/156735
Reviewed-by: Steven Burnett <a0b450117c5d20a22d5c4d52bb8ae13adee003d8@instructure.com>
Product-Review: Steven Burnett <a0b450117c5d20a22d5c4d52bb8ae13adee003d8@instructure.com>
QA-Review: Steven Burnett <a0b450117c5d20a22d5c4d52bb8ae13adee003d8@instructure.com>
Tested-by: Jenkins

djbender/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,instructure/canvas-lms