1e2772d106
TODO: follow-up with an `extensions_test` Change-Id: Ie3d18229daf347885128d02e4b751436a8a0643f Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/159560 Commit-Queue: Phil Quitslund <pquitslund@google.com> Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>