The webkit java applet creation code passes in the baseURL which is typically...

webkit/glue/webframeloaderclient_impl.cc

Index: webkit/glue/webframeloaderclient_impl.cc
===================================================================
--- webkit/glue/webframeloaderclient_impl.cc	(revision 19929)
+++ webkit/glue/webframeloaderclient_impl.cc	(working copy)
@@ -1419,10 +1419,10 @@
 Widget* WebFrameLoaderClient::createJavaAppletWidget(
                                            const IntSize& size,
                                            HTMLAppletElement* element,
-                                           const KURL& url,
+                                           const KURL& /* base_url */,
                                            const Vector<String>& param_names,
                                            const Vector<String>& param_values) {
-  return createPlugin(size, element, url, param_names, param_values,
+  return createPlugin(size, element, KURL(), param_names, param_values,
       "application/x-java-applet", false);
 }