diff -r 9359b006782b -r a5cd79ee1d96 emul/src/main/java/java/lang/Throwable.java
--- a/emul/src/main/java/java/lang/Throwable.java	Mon Jan 14 11:30:56 2013 +0100
+++ b/emul/src/main/java/java/lang/Throwable.java	Mon Jan 21 13:23:23 2013 +0100
@@ -26,6 +26,7 @@
 package java.lang;
 import  java.io.*;
 import org.apidesign.bck2brwsr.core.JavaScriptBody;
+import org.apidesign.bck2brwsr.core.JavaScriptOnly;
 
 /**
  * The {@code Throwable} class is the superclass of all errors and
@@ -234,6 +235,13 @@
     private static final String SELF_SUPPRESSION_MESSAGE = "Self-suppression not permitted";
 
     /** Caption  for labeling causative exception stack traces */
+    @JavaScriptOnly(name="toString", value="function() { return this.toString__Ljava_lang_String_2().toString(); }")
+    private static void jsToString() {
+    }
+    
+    @JavaScriptOnly(name="valueOf", value="function() { return this.toString().valueOf(); }")
+    private static void jsValudOf() {
+    }
     private static final String CAUSE_CAPTION = "Caused by: ";
 
     /** Caption for labeling suppressed exception stack traces */