Fixes T13368. Some workflows (like "Move tasks to...") execute board layout without objects to update. In these cases, we can hit a warning because objectPHIDs is not initialized to array().
- Maniphest Tasks
- T13368: Correct several issues with "Move to Project..." on Workboards
- rP937edcdc580c: Fix a warning in BoardLayoutEngine when no objects are being updated
Went through the "Move tasks to..." workflow on a workboard, no longer saw a warning when trying to iterate over an empty objectPHIDs list.