Purpose: Bug 1180013 : [DataContractJsonSerializer]: Unable to De/Serialize 'ReadOnlyCollection<T>' in a Windows 10 Universal app

Cause: ReadOnlyCollection<T> used to be serializable throught [Serializable] attribute, which is no longer available in N and K.

Solution: Add ReadOnlyCollection<T> to DCS_KnownSerializableGenericTypes list so that DataContract can be created for ReadOnlyCollection<T>.

Note: This is for K only, the fix for N has been checked in. Unit tests have been checked in along with N fix.

[tfs-changeset: 1482134]

Author: SGuyGe

src/System.Private.DataContractSerialization/src/System/Runtime/Serialization/ClassDataContract.cs

@@ -408,7 +408,8 @@ static internal bool IsNonAttributedTypeValidForSerialization(Type type)
                 "System.Tuple`7",
                 "System.Tuple`8",
                 "System.Collections.Generic.Queue`1",
-                "System.Version"
+                "System.Version",
+                "System.Collections.ObjectModel.ReadOnlyCollection`1"
         };
 
         internal static bool IsKnownSerializableType(Type type)