Add support for byte arrays to native messages

runtime/include/dart_api.h

Index: runtime/include/dart_api.h
diff --git a/runtime/include/dart_api.h b/runtime/include/dart_api.h
index 4d8772fb7a5213e1b397758057c1ee8a87e75925..ef76400f9a4fea844c8a336e8c34bca59d9d680d 100755
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -551,6 +551,7 @@ struct Dart_CObject {
     kDouble,
     kString,
     kArray,
+    kByteArray,
     kNumberOfTypes
   };
   Type type;
@@ -563,6 +564,10 @@ struct Dart_CObject {
       int length;
       Dart_CObject** values;
     } as_array;
+    struct {
+      int length;
+      uint8_t* values;
+    } as_byte_array;
   } value;
 };