Refactor Future constructors.

runtime/bin/socket_patch.dart

Index: runtime/bin/socket_patch.dart
diff --git a/runtime/bin/socket_patch.dart b/runtime/bin/socket_patch.dart
index 6f8e72d2471d0173b8677e89a8898e96e75a3666..bb71cc24c981a26192643b5efe87f36b2f093c76 100644
--- a/runtime/bin/socket_patch.dart
+++ b/runtime/bin/socket_patch.dart
@@ -115,11 +115,11 @@ class _NativeSocket extends NativeFieldWrapperClass1 {
     var socket = new _NativeSocket.listen();
     var result = socket.nativeCreateBindListen(address, port, backlog);
     if (result is OSError) {
-      return new Future.immediateError(
+      return new Future.error(
           new SocketIOException("Failed to create server socket", result));
     }
     if (port != 0) socket.localPort = port;
-    return new Future.immediate(socket);
+    return new Future.value(socket);
   }
 
   _NativeSocket.normal() : typeFlags = TYPE_NORMAL_SOCKET {
@@ -699,7 +699,7 @@ class _SocketStreamConsumer extends StreamConsumer<List<int>> {
 
   Future<Socket> close() {
     socket._consumerDone();
-    return new Future.immediate(socket);
+    return new Future.value(socket);
   }
 
   void write() {