[standalone] Don't sort classes in isolates loaded from app snapshots.
[standalone] Don't sort classes in isolates loaded from app snapshots.

Sorting classes causes all generated code to be discarded because it may invalidate embedded CIDs. For the kernel-service in particular, this results in a significant slowdown. These classes were already sorted when the snapshot was generated.

TEST=ci
Change-Id: Ice443718ec43ead88e69039a7c723856f4fd448c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/211882
Commit-Queue: Ryan Macnak <d738b7f001baf9789095d7dc549cff6de60b011d@google.com>
Reviewed-by: Ben Konyi <67ffcaedcc3dc3d87dddb9627b72dd41756b31b1@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