Update Datagram.data to be Uint8List

Bug: #36900
Change-Id: Ia0a4fcb6f21bcb16cb0418bfe9d1b880193fefed
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/104540
Commit-Queue: Todd Volkert <tvolkert@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>

Author: tvolkert

runtime/bin/socket_patch.dart

@@ -1985,6 +1985,6 @@ class _RawDatagramSocket extends Stream<RawSocketEvent>
 
 @pragma("vm:entry-point", "call")
 Datagram _makeDatagram(
-    List<int> data, String address, Uint8List in_addr, int port) {
+    Uint8List data, String address, Uint8List in_addr, int port) {
   return new Datagram(data, new _InternetAddress(address, null, in_addr), port);
 }

sdk/lib/io/socket.dart

@@ -825,12 +825,12 @@ abstract class Socket implements Stream<List<int>>, IOSink {
 }
 
 /**
- * Datagram package. Data send to and received from datagram sockets
+ * Datagram package. Data sent to and received from datagram sockets
  * contains the internet address and port of the destination or source
  * togeter with the data.
  */
 class Datagram {
-  List<int> data;
+  Uint8List data;
   InternetAddress address;
   int port;