rem: Log4js.JSONLayout = function() {return;}; 
add: Log4js.JSONLayout = function() { this.df = new Log4js.DateFormatter(); }; 
context: Log4js.JSONLayout = function() {return;};
meta: 2141	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/2141/b0c58f09c3bf106450447263059885d62b3f736a/log4js.js/buggy/log4js/src/main/js/log4js.js