Per WebIDL, setTimeout should stringify non-string/non-function first arguments.
*** Bug 25441 has been marked as a duplicate of this bug. ***
Created attachment 29903 [details] patch
Comment on attachment 29903 [details] patch you should stop running if toString results in an exception (esp. for setInterval, we don't want a timer for a code that does nothing); Also add tests to cover setInterval
Fixed with Oliver's suggestions implemented in r43046.