删除不遵循 ECMAScript 5/5.1 标准的语法说明

带有条件判断的 catch 或多个 catch 的语句并不在标准内。参考资料：
* https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/try...catch
* ECMAScript 5.0 http://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262%205th%20edition%20December%202009.pdf
* ECMAScript 5.1 http://www.ecma-international.org/ecma-262/5.1/