+ * Fetch a plugin instance of a particular class. Only for testing.
+ * @private
+ * @param {!Class} type The type of the plugin.
+ * @return {Object} Instance of the plugin, or null if there is none.
+ */
+Dygraph.prototype.getPluginInstance_ = function(type) {
+ for (var i = 0; i < this.plugins_.length; i++) {
+ var p = this.plugins_[i];
+ if (p.plugin instanceof type) {
+ return p.plugin;
+ }
+ }
+ return null;
+};
+
+/**