Add ol.Object#unByKey

src/ol/object.exports

@@ -7,5 +7,6 @@
 @exportProperty ol.Object.prototype.setOptions
 @exportProperty ol.Object.prototype.setValues
 @exportProperty ol.Object.prototype.un
+@exportProperty ol.Object.prototype.unByKey
 @exportProperty ol.Object.prototype.unbind
 @exportProperty ol.Object.prototype.unbindAll

src/ol/object.js

@@ -309,6 +309,14 @@ ol.Object.prototype.un = function(type, listener, opt_scope) {
 };
 
 
+/**
+ * @param {?number} key Key.
+ */
+ol.Object.prototype.unByKey = function(key) {
+  goog.events.unlistenByKey(key);
+};
+
+
 /**
  * Removes all bindings.
  */