Update bazel_worker, shelf, oauth2, markdown DEPS to latest versions to enable removing deprecated CONSTANTS.
Update bazel_worker, shelf, oauth2, markdown DEPS to latest versions
to enable removing deprecated CONSTANTS.

Change-Id: Ib8d7fbf7cbb2826dd239f62186a5c4e315b60cff
Reviewed-on: https://dart-review.googlesource.com/64461
Reviewed-by: Nate Bosch <dc212c74d8afde9c690fdd09e74d3e5c5d5a3de0@google.com>

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