Dialogs routed to the LOK client have limited real
estate on the screen because dialogs are rendered
on a canvas. When the listbox drop-down bleeds outside
the dialog area, on the desktop it's no problem, but
in the browser, that requires a larger canvas and
that brings a host of problems.

Here we limit the maximum length of listbox/combobox
drop-down lists to avoid this situation.

This would ideally be configured via ListBoxMaximumLineCount
alas it doesn't work.

Change-Id: I55fff28dbfc59dec36714e221f76cf4160ba1505