Fix http://trac.osgeo.org/openlayers/ticket/3554

Finally using Util.isElement and nothing else for cross-platform
compatibility according to elemoine's comments.

Tested on Chromium 18 Ubuntu 12.04.
8 tests fail (detailed: fail 9). List follows.

23:13:26 test_respectZoom: Google tests can't be run from localhost:8000
23:14:22 test_write_wmc_Layer: Safari has wierd behavior with getElementsByTagNameNS: the result is that we can't run these tests there. Patches welcome.
23:16:15 test_Layer_Google_constructor: Google tests can't be run from localhost:8000
23:16:15 test_clone: Google tests can't be run from localhost:8000
23:16:15 test_Layer_Google_isBaseLayer: Google tests can't be run from localhost:8000
23:16:15 test_Layer_Google_Translation_lonlat: Google tests can't be run from localhost:8000
23:16:15 test_Layer_Google_Translation_pixel: Google tests can't be run from localhost:8000
23:16:15 test_Layer_destroy: Google tests can't be run from localhost:8000
23:16:15 test_Layer_Goole_forwardMercator: Google tests can't be run from localhost:8000
23:16:15 test_Layer_Google_overlay: Google tests can't be run from localhost:8000
23:16:15 test_Layer_Google_isBaseLayer: Google tests can't be run from localhost:8000
23:16:15 test_Layer_Google_setGMapVisibility: Google tests can't be run from localhost:8000
23:20:13 test_Layer_MapServer_Reproject: Can't test google reprojection in Opera or Safari.
23:20:18 test_Layer_WMS_Reproject: Can't test google reprojection in Opera or Safari.
Use protocol relative URL for OSM tiles

OpenStreetMap have enabled SSL on their services and website. Using protocol relative URLs for the tiles takes advantage of this work out of the box.

see: 
  - OSM blog: http://blog.openstreetmap.org/2014/02/11/osm-enhances-user-privacy/
  - specification: [IETF RFC 3986](http://www.ietf.org/rfc/rfc3986.txt) section 4.2
Merge pull request #1248 from mprins/patch-2

Use protocol relative URL for OSM tiles (r=@fredj)
Fix typo.
Merge pull request #446 from candeira/fix_ticket_3554

Fix for trac ticket # 3554 single-arg Map constructor does not work if you pass a DOM element ref