Updated menubar examples ready for review and comment

I have updated the menubar editor and navigation examples  to improve the Javascript code and support for high contrast.

Please review and comment on these two pull requests:

Issue1357 navigation menubar javascript and high contrast compatibility
https://github.com/w3c/aria-practices/pull/1359

ssue1355 update menubar editor javascript and high contrast compatibility
https://github.com/w3c/aria-practices/pull/1356

NOTE: The pull requests include a preview link

Jon Gunderson, Ph.D., CPWA
Coordinator of Accessible IT Group
University of Illinois at Urbana/Champaign
1207 S. Oak Street
Champaign, IL 61820

www: https://go.illinois.edu/jongund