Layer level. This is fix a report from a user: "WMS tiles not loading when map
region crossing international date line(IDL)". All tests continue to pass, and
the lack of this tolerance here seems clear enough given the surrounding code.
Thanks to senthil for the patch, (Closes#2754)
git-svn-id: http://svn.openlayers.org/trunk/openlayers@11708 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf