Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/mscorlib/system/threadstaticattribute.cs

@@ -0,0 +1,30 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+/*============================================================
+**
+** File:        ThreadStaticAttribute.cs
+**
+**
+** Purpose:     Custom attribute to indicate that the field should be treated 
+**              as a static relative to a thread.
+**          
+**
+**
+===========================================================*/
+namespace System {
+    
+    using System;
+
+[Serializable]
+    [AttributeUsage(AttributeTargets.Field, Inherited = false)]
+[System.Runtime.InteropServices.ComVisible(true)]
+    public class  ThreadStaticAttribute : Attribute
+    {
+        public ThreadStaticAttribute()
+        {
+        }
+    }
+}