fix dc parse.

Author: cloudwebrtc

lib/src/rtc_data_channel_impl.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:js_interop';
+import 'package:js/js_util.dart' as jsutil;
 import 'package:web/web.dart' as web;
 import 'package:webrtc_interface/webrtc_interface.dart';
 
@@ -71,8 +72,11 @@ class RTCDataChannelWeb extends RTCDataChannel {
     dynamic arrayBuffer;
     if (data is JSArrayBuffer) {
       arrayBuffer = data.toDart;
+    } else if (data is web.Blob) {
+      arrayBuffer = await jsutil
+          .promiseToFuture(jsutil.callMethod(data, 'arrayBuffer', []));
     } else {
-      arrayBuffer = data.toString();
+      arrayBuffer = data.toDart;
     }
     return RTCDataChannelMessage.fromBinary(arrayBuffer.asUint8List());
   }