[vm] Initialize DartInitializationState in a way MSAN will accept.
[vm] Initialize DartInitializationState in a way MSAN will accept.

TEST=msan
Change-Id: I33cf5c340ed89ce14141282e9a743acc6803f14b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/259061
Commit-Queue: Ryan Macnak <d738b7f001baf9789095d7dc549cff6de60b011d@google.com>
Reviewed-by: Siva Annamalai <2e618a8cbd7bb6b3d4409061ae407d692a098546@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk