Cause: Missing the validator for Work Item Definition asset.
Consequence: If a user creates an invalid Work Item Definition, then the Designer does not show the validator as a service task in the Shape Repo.
Fix: Validation of assets, including Work Item Definitions, has been added back. All assets are validated when saved (and errors reported in the Problems Panel).
Result: The user can now validate an asset without saving it by clicking on a new "validate" button on the editor.