Compare any browser with Firefox (v28.0 on Mac) : events are handled differently. This is due to the <button> tag that has a specific behaviour in Firefox (a <div> element doesn't have such issue).
Click on the button, then click on the (x) in the button, the target of the events will be displayed. The former button has click handlers attached to the button and on the (x), the latter has a click handler attached to the button only.