Need some additional text around add/removeEventListener clearly specifying how equality works

[dtapuska]

Take for example:

var f = function(e) {
};

addEventListener("foo", f, false); /use capture false; mayCancel implicitly true/
addEventListener("foo", f, {useCapture: false, mayCancel: true}); /* this should do nothing; since f is already added with those args. */

Likewise:
removeEventListener("foo", f, {useCapture: false, mayCancel: true}); /* this should remove the first added event listener*/

This slightly differs from the text in http://www.w3.org/TR/dom/#dom-eventtarget-removeeventlistener
as the EventListenerOptions object is likely created and destroyed between add/remove calls so we need to enumerate all the configurations of the options to determine if they are equal. This may be specified somewhere how dictionaries behave; but I haven't found a reference to it.

[RByers]

Covered by #19, eg. here