Registering custom elements are already broken -- see: https://github.com/dart-lang/sdk/issues/49536. There are plans on deleting this code at some point. This current change cleans up dynamic invocations in the deprecated code.
Removes cruft on already-deprecated code and doing it now because I assume dynamic clean up will finish before the issue resolves.
Change-Id: Ic6250c139c5d9b08d88650110f55442a7bf5dd42
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/259247
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Lasse Nielsen <lrn@google.com>
Commit-Queue: Kallen Tu <kallentu@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>
