When an attribute is set as an ID attribute, let the document know so that the corresponding element can be retrieved via getElementById
This fixes the test regard.dom.unitTesting.DOM3.Element.setIdAttributeNS


git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/batik/trunk@1626282 13f79535-47bb-0310-9956-ffa450edef68