Make ZoomToExtent listen on button click

& not its container

src/ol/control/zoomtoextentcontrol.js

@@ -47,7 +47,7 @@ ol.control.ZoomToExtent = function(opt_options) {
   goog.dom.appendChild(button, tip);
   goog.dom.appendChild(element, button);
 
-  goog.events.listen(element, [
+  goog.events.listen(button, [
     goog.events.EventType.TOUCHEND,
     goog.events.EventType.CLICK
   ], this.handleZoomToExtent_, false, this);