bc5008a023
https://github.com/yjbanov/uimatrix is WIP, but already proved useful to highlight areas for some performance improvement. Change-Id: I8f86163e91e276ee4195b7d5c635ffbf3dbaa075 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/325320 Commit-Queue: Alexander Aprelev <aam@google.com> Reviewed-by: Jonas Termansen <sortie@google.com>