Issue 1063: onload doesn't always fire

http://code.google.com/p/google-caja/issues/detail?id=1063
  1. the testbed doesn't pass the extra arg to HtmlEmitter,
     so onload never fires in the testbed.

  2. even when onload does fire, it sometimes doesn't fire.
     cajole this:

    <div>foo</div>
    <script>
    window.onload = function(){cajita.log(1);};
    1;
    </script>

    note that in the cajoled output, there are no calls to
    emitter___.signalLoaded();


Fixed SafeHtmlMaker to make sure that emitter___.signalLoaded()
is always present when there is user supplied JS inline in the
input.


Submitted @3736

[Jasvir, 2009-09-23 20:20:18]

LGTM