[ VM ] Fix issue where IsServiceIsolate may fail in the isolate shutdown callback when the service isolate is shutting down
[ VM ] Fix issue where IsServiceIsolate may fail in the isolate shutdown callback when the service isolate is shutting down

Change-Id: I6dc9786394450ff587ceb45bfa60fd9d40224af6
Reviewed-on: https://dart-review.googlesource.com/55322
Commit-Queue: Ben Konyi <67ffcaedcc3dc3d87dddb9627b72dd41756b31b1@google.com>
Reviewed-by: Siva Annamalai <2e618a8cbd7bb6b3d4409061ae407d692a098546@google.com>

dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk