[vm] Removes support for --causal-async-stacks

All existing embedders have been opted into --lazy-async-stacks, the
VM also uses it as it's default in all configurations.

After this CL, any user of --causal-async-stacks will get an error
message when trying to use it.
=> In any such case, please simply remove the flag.

TEST=Exhaustive CQ.

Bug: https://github.com/dart-lang/sdk/issues/37668
Change-Id: Ia440afcf2dba464aa8b8cf381b93bbac8eb9f8dc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/172564
Commit-Queue: Clement Skau <cskau@google.com>
Reviewed-by: Clement Skau <cskau@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>

https://dart.googlesource.com/sdk/+/2d36c85ff8affb7cbda51e8945180e393c08dd71
1 file changed
tree: d11c25d25b602f7099accb496b5eab1e5c0de4dd
  1. commits.json