Imported Upstream version 6.4.0.137

Former-commit-id: 943baa9f16a098c33e129777827f3a9d20da00d6

mcs/class/System.Private.CoreLib/System.Runtime.InteropServices/InteropExtensions.cs

@@ -0,0 +1,17 @@
+namespace System.Runtime.InteropServices
+{
+	public static class InteropExtensions
+	{
+		public static bool IsBlittable (this object obj)
+		{
+			throw new NotImplementedException ();
+		}
+
+		public static int GetElementSize (this Array array)
+		{
+			if (array == null)
+				throw new ArgumentNullException (nameof (array));
+			return Marshal.GetArrayElementSize (array.GetType ());
+		}
+	}
+}