assertion in javascript: debugger statement stops in idea for chrome but not for firefox

Hi
I wrote an assertion function which uses the javascript debugger statement.
when debugging in chrome the debugger stops at  javascript debugger statement inside the idea
However in firefox it seems that the browser takes over and I do not hit the 'debugger' in the idea , I see the firefox debugger stop at the line
I would like firefox to behave like IE.
thanks.