Fix return type of native methods to match the implementation.
(These native implementations do not throw an exception, instead they
return on OSError object).

Related to the error seen in https://github.com/dart-lang/sdk/issues/48456

Change-Id: I6c98687d069073c4aa9d0344e79e777024590541
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/234662
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Siva Annamalai <asiva@google.com>

sdk/lib/_internal/vm/bin/sync_socket_patch.dart

diff --git a/sdk/lib/_internal/vm/bin/sync_socket_patch.dart b/sdk/lib/_internal/vm/bin/sync_socket_patch.dart
index 708a1e7..beff01e 100644
--- a/sdk/lib/_internal/vm/bin/sync_socket_patch.dart
+++ b/sdk/lib/_internal/vm/bin/sync_socket_patch.dart
@@ -307,9 +307,9 @@
   @pragma("vm:external-name", "SynchronousSocket_CloseSync")
   external _nativeCloseSync();
   @pragma("vm:external-name", "SynchronousSocket_GetPort")
-  external int _nativeGetPort();
+  external _nativeGetPort();
   @pragma("vm:external-name", "SynchronousSocket_GetRemotePeer")
-  external List _nativeGetRemotePeer();
+  external _nativeGetRemotePeer();
   @pragma("vm:external-name", "SynchronousSocket_Read")
   external _nativeRead(int len);
   @pragma("vm:external-name", "SynchronousSocket_ReadList")