Update to core-js 3
Created by: felixfbecker
This is a re-revert of https://github.com/sourcegraph/sourcegraph/pull/4117
I was unable to reproduce the original issue:
Created by: felixfbecker
This is a re-revert of https://github.com/sourcegraph/sourcegraph/pull/4117
I was unable to reproduce the original issue: