fa7cadde80
I/O can take arbitrarily long, and open interior pointers prevent all other isolates in the group to reaching safepoints. TEST=ci Bug: https://github.com/flutter/flutter/issues/140763 Change-Id: I1fa732d0db31500946aee232dc31f5baf324a55e Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/345746 Commit-Queue: Ryan Macnak <rmacnak@google.com> Reviewed-by: Brian Quinlan <bquinlan@google.com>