Fastfix: Original can be undefined

[jbrumwell]

Fixes pageX, pageY and which for when the original event does not exist and
the original value is undefined.

I was working with a jquery plugin that invokes mousemove like so

/trigger mousemove to move the knob to the current position
            $(document).on({
                mousemove: $.proxy(this.mousemove, this),
                mouseup: $.proxy(this.mouseup, this)
}).trigger('mousemove');

Since the mousemove handler handles actually mouse movements and this custom event, when calling:

var something = e.pageX || someothervalue;

It causes and error "original is undefined" I have not needed the which event but it most likely suffers from the same issue.

[daffl]

Good point. It seems as if every special mapping should have a

if(!original) {
    return;
}

As relatedTarget already does.

[daffl]

I fixed it with the snippet I mentioned. Let me know if there are any problems with that.