Fix gateway timeout typo - issue #4930.

Review at: http://gwt-code-reviews.appspot.com/1618805/
Patch by: stephenh

Review by: skybrian@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10940 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/user/src/com/google/gwt/http/client/Response.java b/user/src/com/google/gwt/http/client/Response.java
index 554f2af..a154159 100644
--- a/user/src/com/google/gwt/http/client/Response.java
+++ b/user/src/com/google/gwt/http/client/Response.java
@@ -34,7 +34,7 @@
   public static final int SC_CREATED = 201;
   public static final int SC_EXPECTATION_FAILED = 417;
   public static final int SC_FORBIDDEN = 403;
-  public static final int SC_GATEWAY_TIMEOUT = 405;
+  public static final int SC_GATEWAY_TIMEOUT = 504;
   public static final int SC_GONE = 410;
   public static final int SC_HTTP_VERSION_NOT_SUPPORTED = 505;
   public static final int SC_INTERNAL_SERVER_ERROR = 500;