javascript missing after property id 高手来！

这个问题是firefox 调试出来的。纠结了几天了。
JScript code:
function Map() {
this.keys = new Array();
this.data = new Object();
this.put = function(key, value) {
if(this.data[key] == null){
this.keys.push(key);
}
this.data[key] = value;
return this;
};
this.get = function(key) {
return this.data[key];
};
this.remove = function(key) {
this.keys.remove(key);
this.data[key] = null;
};
this.each = function(fn){
if(typeof fn != 'function'){
return;
}
var len = this.keys.length;
for(var i=0;i<len;i++){
var k = this.keys[i];
fn(k,this.data[k],i);
}
};
this.entrys = function() {
var len = this.keys.length;
var entrys = new Array(len);
for (var i = 0; i < len; i++) {
entrys[i] = {
key : this.keys[i],
value : this.data[i]
};
}
return entrys;
};
this.isEmpty = function() {
return this.keys.length == 0;
};
this.size = function(){
return this.keys.length;
};
this.toString = functio