Expandable grid tutorial is broken

[flyingbertman]

The expandable grid tutorial has render issues when all sub grids are expanded where the rows disappear. It's easy to replicate

1. Go to http://ui-grid.info/docs/#!/tutorial/Tutorial:%20216%20Expandable%20grid
2. Scroll down to the first grid demonstration
3. Click "Toggle Expand All Visibility"
4. Scroll down the grid a little way, the rows all disappear.

Similar issues reported here.
#3473
#4508