This CL cleans up the logic in two tests to better prepare for Dart2Wasm. In addition, env_test has been cleaned up now that the multitest no longer makes sense.
Change-Id: I0a7eabff1e2bfb6ea7aa1078ee85a58db9886e21
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/267286
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Joshua Litt <joshualitt@google.com>