When users scroll while dragging items, update item positions immediately
Summary:
Fixes T5979. When you drag a task and scroll using the mouse wheel, we don't move the task under your cursor until you move the mouse.
Instead, listen for scroll and move the task.
Test Plan:
- Clicked and dragged a task.
- While holding the task and not moving the cursor, used the mouse wheel to scroll.
- The task followed the cursor (previously, it stayed in position until the mouse was moved again).
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T5979
Differential Revision: https://secure.phabricator.com/D10416