This change tries to run from dartdev.dart.snapshot and falls back to
running from dartdev.dill if incompatible VM flags are provided.
Fixes https://github.com/dart-lang/sdk/issues/43969
Performance results:
dart test.dart (no CLI isolate): 0.167s
dart run test (from snapshot): 0.208s
dart run test (from kernel): 0.326s
TEST=pkg/dartdev/test/load_from_dill_test.dart
Change-Id: I3195886b86676580ef2a0221f0284328964ef061
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/178300
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>