TreeNode $$treeLevel logic is wrong

If you want A ....A.1 ....A.2 ....A.3 B ....B.1 ....B.2 C D E

there is currently no way to inform the grid that C above does not have, and will never have children, and should not be a row-header.

Currently, the only way to ensure an item is not a row header is to set the $$treeLevel = undefined. *This allows the following to pass: *{'ui-grid-tree-header-row': row.treeLevel > -1}

However... The problem with this is row C above will always be bolded. B.2 has $$treeLevel = undefined, is a child of B, so it's OK C has $$treeLevel = null, which makes it correctly not a child of B, BUT, internally, it gets wrongly assigned to row.treeLevel =1, or something... actually not sure how it's passing the test.

See Plunker Demo In this example, "Morgan Sanford", row 45, should not be bold, it has no children. And, setting "Toggle Expand No Children" only partly helps, because the row is still bolded.