Memory leak with multiple removed handlers on the same element

[phillipskevin]

Due to the way the removed event handler is set and cleaned up, the last registered removed event will always be the one that is called and then removed. This causes a memory leak since the second handler is never turned off().

Here is an example:

var $el = $("<div>");

var teardownOne = function() { ... }; // this will be called
var teardownTwo = function() { ... }; // this will not be called

domEvents.addEventListener.call($el[0], "removed", teardownOne);
domEvents.addEventListener.call($el[0], "removed", teardownTwo);

domEvents.removeEventListener.call($el[0], "removed", teardownOne);

...
$el.remove();

[phillipskevin]

This is another part of canjs/canjs#3147.