Thanks Marc Jansen for this nice contribution. Without wanting
to gush, I think this should be a model contribution because:
1. it is a simple change
2. with a nice example that clearly demonstrates the benefit
3. it includes tests!
4. and Marc wrote a note to the dev list with links to the ticket
r = me (closes#2266)
git-svn-id: http://svn.openlayers.org/trunk/openlayers@9720 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
