Fix BazelWorkspacePackageTest on Windows.
Fix BazelWorkspacePackageTest on Windows.

R=1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com, paulberry@google.com

Change-Id: Ie0be91f58bf6f3e0fed1410b6761d16ff07cb327
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/128563
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Commit-Queue: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@google.com>

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