There are uses of flags before the VM snapshot gets read, so we need to
move the "snapshot sniffing" code to the very beginning of Dart::Init().
Due to the fact that FullSnapshotReader/Deserializer assume there is a
[Thread] available - and we don't have a [Thread] yet when we should
process the flags - this CL moves version/feature logic into a new
[SnapshotHeaderReader] class which does not depend on Thread/...
Change-Id: I38a45041f0696b96e44fc2b294e3442a5fba1a81
Reviewed-on: https://dart-review.googlesource.com/c/90941
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Martin Kustermann
51bc367806