Fix breadcrumb resizing in non-chrome browsers
Fix breadcrumb resizing in non-chrome browsers

this would break in browsers that don’t have requestIdleCallback.
It is fine to write `window.propertyThatDoesntExist` but not just
`propertyThatDoesntExist` the latter will say 
“Uncaught ReferenceError: propertyThatDoesntExist is not defined”

I just barely added this 4 days ago so if we merge it before branching
Beta we won’t need to warmfix it

Test plan:
* breadcrumbs should resize fine in non browsers that don’t support
  requestIdleCallback (https://caniuse.com/#search=requestIdleCallback)
  eg: safari and edge

Change-Id: I711410e54af5e73afab2d5dcbaa9a7e0c778ae4d
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/213785
Tested-by: Jenkins
Reviewed-by: Brent Burgoyne <bccf16d7abdd2611580b1cd7d7a6fcc150d619da@instructure.com>
QA-Review: Brent Burgoyne <bccf16d7abdd2611580b1cd7d7a6fcc150d619da@instructure.com>
Product-Review: Brent Burgoyne <bccf16d7abdd2611580b1cd7d7a6fcc150d619da@instructure.com>

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