This reapplies commit 0c05e33836
and reverts the revert 029e0cec71.
Tested: Added few new tests, updated existing. Mainly regression testing.
CoreLibraryReviewExempt: Reviewed in original CL.
Change-Id: Ifcc79ce2f9375f607722643a04957b0961e6c295
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/284304
Reviewed-by: Ömer Ağacan <omersa@google.com>
Commit-Queue: Lasse Nielsen <lrn@google.com>
Reviewed-by: Aske Simon Christensen <askesc@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>