Mark CharEnumerator as [Serializable] (#11124)

Fixes https://github.com/dotnet/corefx/issues/18704

diff --git a/src/mscorlib/shared/System/CharEnumerator.cs b/src/mscorlib/shared/System/CharEnumerator.cs
index ea9915a..4dbd5cd 100644 (file)
--- a/src/mscorlib/shared/System/CharEnumerator.cs
+++ b/src/mscorlib/shared/System/CharEnumerator.cs
@@ -17,6 +17,7 @@ using System.Collections.Generic;
 
 namespace System
 {
+    [Serializable]
     public sealed class CharEnumerator : IEnumerator, IEnumerator<char>, IDisposable, ICloneable
     {
         private String _str;