Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

mcs/class/corlib/System.Text/EncodingHelper.WebAssembly.cs

@@ -0,0 +1,34 @@
+#if WASM
+
+using System;
+
+namespace System.Text {
+
+	internal static partial class EncodingHelper {
+
+		static volatile Encoding utf8Encoding;
+
+		internal static Encoding UTF8 {
+			get {
+				if (utf8Encoding == null) {
+					lock (lockobj){
+						if (utf8Encoding == null){
+							utf8Encoding = new UTF8Encoding (true, false);
+							utf8Encoding.setReadOnly ();
+						}
+					}
+				}
+
+				return utf8Encoding;
+			}
+		}
+
+		// The mobile profile has been default'ing to UTF8 since it's creation
+		internal static Encoding GetDefaultEncoding ()
+		{
+			return UTF8;
+		}
+	}
+}
+
+#endif