fix nav in high contrast according the changes in master branch

[Leolewin]

Pull request checklist

• Addresses an existing issue: Fixes #0000
• Include a change request file using $ yarn change

Description of changes

Port 13850 to update Nav to latest redlines in office-ui-fabric-react/5.79.1

Focus areas to test

(optional)

[ghost]

All CLA requirements met.

[khmakoto]

Thanks for submitting this fix, but due to work we're currently doing to prepare master for our version 8 beta release, we're asking contributors to either wait a couple weeks to submit fixes (if it's not urgent) or submit to the new 7.0 branch (if it's urgent). See #15222 for more details.

[msft-github-bot]

This pull request has been automatically marked as stale because it was marked as requiring author feedback but has not had any activity for 7 days. It will be closed if no further activity occurs within 5 days of this comment. Thank you for your contributions to Fluent UI!

[Leolewin]

Thanks for submitting this fix, but due to work we're currently doing to prepare master for our version 8 beta release, we're asking contributors to either wait a couple weeks to submit fixes (if it's not urgent) or submit to the new 7.0 branch (if it's urgent). See #15222 for more details.

Hi, @khmakoto , how about the feedback of version 8 beta release? We have a accessibility bug in SharePoint 2019 caused by it and this PR is sent to settle the issue. I have sent a email to fabric team before and didn't get any response. So is there any one who can review my changes, reopen this PR and merge it into branch microsoft:office-ui-fabric-react_v5.79.1? Thanks

Other branch is targeted.

[khmakoto]

Hi @Leolewin, didn't meant for the PR to close, I've reopened it for now after seeing that another branch is being targeted. Sorry for that.

@ecraig12345 are you the one that should review this change?

[Leolewin]

Hi @Leolewin, didn't meant for the PR to close, I've reopened it for now after seeing that another branch is being targeted. Sorry for that.

@ecraig12345 are you the one that should review this change?

@khmakoto Thanks for your great help.