Eclipse的Jar包解压出System.js里String与Boolean定义分号可有可无吗？

Eclipse的Jar包解压出System.js里String与Boolean定义分号可有可无吗？

org.eclipse.wst.jsdt.core_1.3.300.v201410221502\libraries\system.js
/**
* Object String()
* @constructor
* @extends Object
* @since Standard ECMA-262 3rd. Edition
* @since Level 2 Document Object Model Core Definition.
*/
function String(){}
String.prototype = new Object();

/**
* Object Number()
* @constructor
* @extends Object
* @since Standard ECMA-262 3rd. Edition
* @since Level 2 Document Object Model Core Definition.
*/
function Number(){}
Number.prototype = new Object();

/**
* Object Boolean()
* @constructor
* @extends Object
* @since Standard ECMA-262 3rd. Edition
* @since Level 2 Document Object Model Core Definition.
*/
function Boolean(){};
Boolean.prototype = new Object();

/**
* Object Date(s)
* @constructor
* @param {String} s
* @extends Object
* @since Standard ECMA-262 3rd. Edition
* @since Level 2 Document Object Model Core Definition.
*/
function Date(s){};
Date.prototype = new Object();

Boolean和Date声明后的大括号后有分号，而String和Number却没有？这是为毛？
这可是从Eclipse带的jar包里解压出来的system.js文件。修改