This is to ensure that deferred library status is per isolate, rather than per isolate-group.
TEST=deferred_isolate_test.dart
Issue dartbug.com/36097
Change-Id: I1fb8b8f1830aac688a078fe0a82b06c7daa856fa
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/184040
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>