Fix resize event.target bug in Firefox

[davekinkead]

The resize event is attached to window and on scroll, the event.target is the map canvas in Chrome & Safari but resolves to the canvas' parent (mapper.DOM) in Firefox. This means the zoom function doesn't work because return

Any ideas why this is happening @geoffreyd ? should be a very easy fix but I'm stumped!

[geoffreyd]

@davekinkead is there a specific test page this is happening on? I've tried the code both before and after the fixes you put in, but my firefox is always returning the canvas element.

[davekinkead]

hi @geoffreyd hope all is well ... crazy times here so will get back to you when I can.