gistfile1.js

var WebSocket = null;

hiddenFrames.add(hiddenFrames.HiddenFrame({
	'onReady': function () {
		var self = this; // Don't use bind for `this` since GCC warns w/ "dangerous use of the global this object"
		self.element.contentWindow.location = require("sdk/self").data.url("ui/hidden.html");
		self.element.addEventListener("DOMContentLoaded", function () {
			console.log("Initializing WebSocket for '" + self.element.contentWindow.location + "'");
			//noinspection JSUnresolvedVariable
			WebSocket = self.element.contentWindow.MozWebSocket || self.element.contentWindow.WebSocket;
		}, true, true);
	}
}));