Optimized access to ByteString from coded io.
diff --git a/src/ProtocolBuffers/CodedInputStream.cs b/src/ProtocolBuffers/CodedInputStream.cs
index 225cf4d..a9afbe6 100644
--- a/src/ProtocolBuffers/CodedInputStream.cs
+++ b/src/ProtocolBuffers/CodedInputStream.cs
@@ -58,7 +58,7 @@
     /// TODO(jonskeet): Consider whether recursion and size limits shouldn't be readonly,

     /// set at construction time.

     /// </remarks>

-    public sealed class CodedInputStream

+    public sealed partial class CodedInputStream

     {

         private readonly byte[] buffer;

         private int bufferSize;

@@ -353,7 +353,7 @@
             else

             {

                 // Slow path:  Build a byte array first then copy it.

-                return ByteString.CopyFrom(ReadRawBytes(size));

+                return ByteString.AttachBytes(ReadRawBytes(size));

             }

         }