fix doc comments in dart:io and collection types

sdk/lib/io/sync_socket.dart

Index: sdk/lib/io/sync_socket.dart
diff --git a/sdk/lib/io/sync_socket.dart b/sdk/lib/io/sync_socket.dart
index cc055a7f9d6be171d01663dca61646e2d80f83a1..fee259da5e87de7d2d433dcbd1fa8b14dfd74981 100644
--- a/sdk/lib/io/sync_socket.dart
+++ b/sdk/lib/io/sync_socket.dart
@@ -68,8 +68,9 @@ abstract class RawSynchronousSocket {
    * Shutdown a socket in the provided direction.
    *
    * Calling shutdown will never throw an exception and calling it several times
-   * is supported. If both [RECEIVE] and [SEND] directions are closed, the
-   * socket is closed completely, the same as if [closeSync] has been called.
+   * is supported. If both [SocketDirection.RECEIVE] and [SocketDirection.SEND]
+   * directions are closed, the socket is closed completely, the same as if
+   * [closeSync] has been called.
    */
   void shutdown(SocketDirection direction);