Call refresh before checking the splitter sizes.

If we don't do this, we miss the "current" size when an output pane
has just been shown (it comes out as 0) and we resize it to the
minimum size.

Task-number: QTCREATORBUG-8877
Change-Id: I8b1cc19d116dde6edcf8770bb36d1598dfdce195
Reviewed-by: Eike Ziller <eike.ziller@digia.com>