This CL adds acquisiton of write lock and check for whether write lock is held when updating class functions, primarily populated during class finalization. Read locks will be added in successive CLs, so is extending of the locks coverage to all aspects of program structure changes.
Bug: https://github.com/dart-lang/sdk/issues/36097
Change-Id: I3dba6bc23db4e45599a20717226210f12e7fd2b3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/168140
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>