Fix Silverlight build error
Fix Silverlight build error

MindTouch/NServiceKit,NServiceKit/NServiceKit,NServiceKit/NServiceKit,ZocDoc/ServiceStack,ZocDoc/ServiceStack,timba/NServiceKit,MindTouch/NServiceKit,NServiceKit/NServiceKit,timba/NServiceKit,nataren/NServiceKit,NServiceKit/NServiceKit,MindTouch/NServiceKit,ZocDoc/ServiceStack,nataren/NServiceKit,ZocDoc/ServiceStack,timba/NServiceKit,nataren/NServiceKit,nataren/NServiceKit,MindTouch/NServiceKit,timba/NServiceKit