[cleanup] Use Set and remove lint ignores from Object.ts
[cleanup] Use Set and remove lint ignores from Object.ts

R=8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org, dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org

Bug: None
Change-Id: I792f612eb0650d447c692574b2c465be43155c48
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2974926
Reviewed-by: Paul Lewis <8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org>
Reviewed-by: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>
Commit-Queue: Simon Zünd <38944668e9e2ca98ccd0275b53370f90fa55c113@chromium.org>

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