Enable Firebug Lite in a JavaFX WebView.

Firebug.java

	if (isDebugging())
    		engine.documentProperty().addListener(new ChangeListener<Document>() {
    			@Override
    			public void changed(ObservableValue<? extends Document> prop, 
    					    Document oldDoc, Document newDoc) {
    				enableFirebug(engine);
    			}
    		});

    	/**
	 * Enables Firebug Lite for debugging a webEngine.
	 * @param engine the webEngine for which debugging is to be enabled.
	 */
	private static void enableFirebug(final WebEngine engine) {
		engine.executeScript("if (!document.getElementById('FirebugLite')){E = document['createElement' + 'NS'] && document.documentElement.namespaceURI;E = E ? document['createElement' + 'NS'](E, 'script') : document['createElement']('script');E['setAttribute']('id', 'FirebugLite');E['setAttribute']('src', 'https://getfirebug.com/' + 'firebug-lite.js' + '#startOpened');E['setAttribute']('FirebugLite', '4');(document['getElementsByTagName']('head')[0] || document['getElementsByTagName']('body')[0]).appendChild(E);E = new Image;E['setAttribute']('src', 'https://getfirebug.com/' + '#startOpened');}"); 
	}