R1:7a0090f4d070

Fix an issue where the "viewer" is not passed to Bulk Edit controls properly

Summary:
See PHI1442. If you have a bulk-editable datasource field with a composite datasource, it can currently fatal on the bulk edit workflow because the viewer is not passed correctly.

The error looks something like this:

> Argument 1 passed to PhabricatorDatasourceEngine::setViewer() must be an instance of PhabricatorUser, null given, called in…