(JSScriptingHandler) Really fix the freeze when parsing scripts with errors

To do that, properly use Rhino error reporting system
(ScriptingHandler) Handle multiple errors on one single line
(JSScriptingHandlerRhino) Remove the recursivity in processerrors

The recursivity is not needed anymore now that we handle errors with
the error reporter.
Removing the recursive call to interpret avoids completely the possibility of an infinite loop...