This test verifies that the load event doesn't fire until subresource content has loaded, even if you manually call document.close beforehand. See bug 13241.

dimensions before onload (should be { 0 x 0 }, otherwise the test will falsely pass): { 0 x 0 }
dimensions during onload (should be { 215 x 174 }, otherwise onload fired too early): { 215 x 174 }