Print exception trace inside Kit.codeBug() to have it even if the execption is shadowed by another one

js/rhino/src/org/mozilla/javascript/Kit.java

@@ -397,7 +397,10 @@ public class Kit
     public static RuntimeException codeBug()
         throws RuntimeException
     {
-        throw new IllegalStateException("FAILED ASSERTION");
+        RuntimeException ex = new IllegalStateException("FAILED ASSERTION");
+        // Print stack trace ASAP
+        ex.printStackTrace(System.err);
+        throw ex;
     }
 }