Changes to NSScrollView decoding

[Fred Kiefer]

I just added a patch from Quentin for the decoding of NSScrollView. The
details for this can be found in the bug report #27311.

I added some more changes to this patch and would recommend that
especially Gregory should check whether his code still works. The is a
(now commented out) piece of code in this methods that is really strange
and should never have been needed (with [self tile] correctly placed).
But then Greg never gave the example code that justified this code and I
might have broken something here.

Fred