SyntaxError: Unexpected token (STRING, "'use strict'")

[pylover]

SyntaxError: Unexpected token (STRING, "'use strict'") at 1:4492 between LexToken(ID,'\xef',1,4489) and LexToken(SEMI,';',1,4504)

js contents:

'use strict';

// Add ECMA262-5 method binding if not supported natively
//
if (!('bind' in Function.prototype)) {
Function.prototype.bind= function(owner) {
var that= this;
if (arguments.length<=1) {
return function() {
return that.apply(owner, arguments);
};
} else {
var args= Array.prototype.slice.call(arguments, 1);
return function() {
return that.apply(owner, arguments.length===0? args : args.concat(Array.prototype.slice.call(arguments)));
};
}
};
}