Migrate to private class fields in core/root
Migrate to private class fields in core/root

R=8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org

Bug: 1222126
Change-Id: Ia4f04146359fc5f775a12efab6ada66137449a87
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3201675
Commit-Queue: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>
Reviewed-by: Paul Lewis <8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend