Add a web socket client

runtime/bin/http.dart

Index: runtime/bin/http.dart
diff --git a/runtime/bin/http.dart b/runtime/bin/http.dart
index b0ebda607ee356eec82d8935365890a4a9b7112f..823cebec87326ba25754339625dedf2a80929516 100644
--- a/runtime/bin/http.dart
+++ b/runtime/bin/http.dart
@@ -388,10 +388,10 @@ interface HttpResponse default _HttpResponse {
    * socket is detached the HTTP server will no longer perform any
    * operations on it.
    *
-   * This is normally used when a HTTP upgraded request is received
+   * This is normally used when a HTTP upgrade request is received
    * and the communication should continue with a different protocol.
    */
-  Socket detachSocket();
+  DetachedSocket detachSocket();
 }
 
 
@@ -485,6 +485,16 @@ interface HttpClientConnection {
    * connecting or processing the HTTP request.
    */
   void set onError(void callback(e));
+
+  /**
+   * Detach the underlying socket from the HTTP client. When the
+   * socket is detached the HTTP client will no longer perform any
+   * operations on it.
+   *
+   * This is normally used when a HTTP upgrade is negotiated and the
+   * communication should continue with a different protocol.
+   */
+  DetachedSocket detachSocket();
 }
 
 
@@ -550,6 +560,19 @@ interface HttpClientResponse default _HttpClientResponse {
 }
 
 
+/**
+ * When detaching a socket from either the [:HttpServer:] or the
+ * [:HttpClient:] due to a HTTP connection upgrade there might be
+ * unparsed data already read from the socket. This unparsed data
+ * together with the detached socket is returned in an instance of
+ * this class.
+ */
+interface DetachedSocket default _DetachedSocket {
+  Socket get socket();
+  List<int> get unparsedData();
+}
+
+
 class HttpException implements Exception {
   const HttpException([String this.message = ""]);
   String toString() => "HttpException: $message";