Remove old unused Web Socket code.

sdk/lib/_internal/pub/lib/src/barback/barback_server.dart

Index: sdk/lib/_internal/pub/lib/src/barback/barback_server.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback/barback_server.dart b/sdk/lib/_internal/pub/lib/src/barback/barback_server.dart
index 954658b600eb797c3360b84674d77538fd9b4ca5..e42ef03d5948084aac02929567b3ea1137994b70 100644
--- a/sdk/lib/_internal/pub/lib/src/barback/barback_server.dart
+++ b/sdk/lib/_internal/pub/lib/src/barback/barback_server.dart
@@ -40,11 +40,6 @@ class BarbackServer extends BaseServer<BarbackServerResult> {
   /// If this is `null`, all assets may be served.
   AllowAsset allowAsset;
 
-  // TODO(rnystrom): Remove this when the Editor is using the admin server.
-  // port. See #17640.
-  /// All currently open [WebSocket] connections.
-  final _webSockets = new Set<WebSocket>();
-
   /// Creates a new server and binds it to [port] of [host].
   ///
   /// This server will serve assets from [barback], and use [rootDirectory] as
@@ -61,15 +56,6 @@ class BarbackServer extends BaseServer<BarbackServerResult> {
       this.rootDirectory)
       : super(environment, server);
 
-  // TODO(rnystrom): Remove this when the Editor is using the admin server.
-  // port. See #17640.
-  /// Closes the server.
-  Future close() {
-    var futures = [super.close()];
-    futures.addAll(_webSockets.map((socket) => socket.close()));
-    return Future.wait(futures);
-  }
-
   /// Converts a [url] served by this server into an [AssetId] that can be
   /// requested from barback.
   AssetId urlToId(Uri url) {