Make WebSocket.fromSocket public.

sdk/lib/io/websocket.dart

Index: sdk/lib/io/websocket.dart
diff --git a/sdk/lib/io/websocket.dart b/sdk/lib/io/websocket.dart
index 32dc9e065ea13c36c1a62fa3af7891edd9cc7d1a..a35ca3e5eb6852ee9698561b39c463d9e7230d6e 100644
--- a/sdk/lib/io/websocket.dart
+++ b/sdk/lib/io/websocket.dart
@@ -134,6 +134,25 @@ abstract class WebSocket implements Stream, StreamSink {
       _WebSocketImpl.connect(url, protocols);
 
   /**

[kasperl, 2014/05/05 09:31:51]

How bad would it be to add a (deprecated) default constructor for this so that
people can subclass this for the time being?

[Anders Johnsen, 2014/05/05 09:33:49]

Would it be okay if the WebSocket constructor throw a UnimplementedError?

[nweiz, 2014/05/05 19:21:03]

Wouldn't that also break users using "extend WebSocket"?

+   * Creates a WebSocket from an already-upgraded socket.
+   *
+   * The initial WebSocket handshake must have occurred prior to this call. A
+   * WebSocket client can automatically perform the handshake using
+   * [WebSocket.connect], while a server can do so using
+   * [WebSocketTransformer.upgrade]. To manually upgrade an [HttpRequest],
+   * [HttpRequest.detachSocket] may be called.
+   *
+   * [protocol] should be the protocol negotiated by this handshake, if any.
+   *
+   * If [serverSide] is `false`, the WebSocket will act as the client and mask
+   * the messages it sends. If it's `true`, it will act as the server and will
+   * not mask its messages.
+   */
+  factory WebSocket.fromUpgradedSocket(Socket socket, {String protocol,
+        bool serverSide: true}) =>
+      new _WebSocketImpl._fromSocket(socket, protocol, serverSide);
+
+  /**
    * Returns the current state of the connection.
    */
   int get readyState;