Firefox 3 Java Bug with openinfocard

Just filed a bug for Firefox 3 and Java 6 Update 10 RC.

I maintain the Firefox extension "openinfocard"
http://code.google.com/p/openinfocard/downloads/list
Since Firefox3 users experience an error message "ReferenceError: java is not
defined". Today I tried whether this error still occurs with
jdk-6u10-rc-bin-b28-windows-i586-p-21_jul_2008.exe and ran into the error
message.
"TypeError: invalid 'instanceof' operand java.net.URLClassLoader" here:
http://code.google.com/p/openinfocard/source/browse/trunk/firefox/components/TokenComponent.js#272
This works with previous version of java.

Reproducible: Always

Steps to Reproduce:
1. Install the Firefox extension into FF3. Save to disk, then install.
2. navigate to a site that uses Information Cards e.g.
https://wag.bandit-project.org/BanditIdP/index.jsp
3. Click on the Information Card icon
Actual Results:
An alert dialog opens with the error message "TypeError: invalid 'instanceof'
operand java.net.URLClassLoader

Expected Results:
No alert but the identity card selector window opens and you can create an
information card (self-issued) that you can then use to provide your claims
about yourself.