Remove blur action on MOUSEOUT on Zoom Out button

This is a follow up of commit 761aa0ea5c.
That commit removed ol.control.Control.bindMouseOutFocusOutBlur function,
but forgot to remove this piece of code here.

src/ol/control/zoomcontrol.js

@@ -58,13 +58,6 @@ ol.control.Zoom = function(opt_options) {
       goog.events.EventType.CLICK, goog.partial(
           ol.control.Zoom.prototype.handleClick_, -delta), false, this);
 
-  goog.events.listen(outElement, [
-    goog.events.EventType.MOUSEOUT,
-    goog.events.EventType.FOCUSOUT
-  ], function() {
-    this.blur();
-  }, false);
-
   var cssClasses = className + ' ' + ol.css.CLASS_UNSELECTABLE + ' ' +
       ol.css.CLASS_CONTROL;
   var element = goog.dom.createDom(goog.dom.TagName.DIV, cssClasses, inElement,