e88020be9a
This moves the checking of duplicates, member/setter, and static/instance conflicts to a _PreBuilder. Change-Id: I85f33750c1579676696223d1b19019887ae41e50 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/397163 Reviewed-by: Erik Ernst <eernst@google.com> Commit-Queue: Johnni Winther <johnniwinther@google.com>