Issue 499; Fix problem with addEventListener for load events on flash handler object _SVGWindow fake object.
Issue 499; Fix problem with addEventListener for load events
on flash handler object _SVGWindow fake object.

Also, fix this for native handler. Firefox does not appear to populate
SVGDocument.readyState, so we call the listener immediately. 
This may not be technically correct. However, if addEventListener
is being called on the patched window, then the svg script code is
already running and so the svg document is probably ready
enough to fire the load event. In practice, this appears to be the case.
Moreover, calling the listener even if the document is not fully ready
is better than the current behavior of never firing the event at all.


leymannx/svgweb,leymannx/svgweb,leymannx/svgweb,leymannx/svgweb,leymannx/svgweb