Taskboard display is messed up when the last parent task is expanded in IE7.

In IE7, when the last parent task in the list is expanded, the existing row of tasks doesn't move down out of the way to make room for the newly-displayed subtasks; they end up overlapping.

e.g.
1) https://qa-jac.atlassian.com/secure/TaskBoard.jspa?selectedProjectId=12200&selectedBoardId=14863
2) Expand GHS-1665 (or the last entry if the data have changed)