Editor: Don't throw an exception on null views when closing all buffers.
http://bugs.activestate.com/show_bug.cgi?id=100508
rn=

(integrated from komodo (trunk) change 82110 by ericp)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@13670 b87d16e7-d29f-4ee1-b5ec-817d645d335f