[Mono-dev] Partial redo of r90413

[Konstantin Triger]

Hi Eno,

You reverted r90413 in r90445 because one of Asserts failed on .Net (all the rest did not and actually were the prove for the fix). 

Since this revert broke our internal tests, I removed the broken assert, added more testing and committed
the patch again under TARGET_JVM in r92606.

Please review the patch and if you find it correct remove the TARGET_JVM.

Note that even after the patch we behave slightly different than MS.Net, because they return Unspecified kind for XmlConvert.ToDateTime ("2006-05-30T09:48:32.0Z", XmlDateTimeSerializationMode.Unspecified), but we return Local. Their behavior looks buggy for me.

Regards,
Kosta