2005-10-23 Atsushi Enomoto <atsushi@ximian.com>

2005-10-23  Atsushi Enomoto <atsushi@ximian.com>

	* XmlTextReader.cs, DTDValidatingReader.cs : LookupNamespace("") for
	  default namespace was returning "" instead of null. It didn't check
	  empty namespace URI for non-empty prefixes.

	* XmlTextReaderTests.cs, XmlValidatingReaderTests.cs,
	  XmlReaderCommonTests.cs : added and fixed tests to make sure that
	  LookupNamespace("") returns null for default namespace, and checks
	  that empty namespace URI is not allowed for non-empty prefix.

svn path=/trunk/mcs/; revision=52099