MapInstance.Set() does not overwrite existing values

[kpreisser]

Hi,

when running the following code in Firefox, Chrome or other browsers:

new Map().set(1, 2).set(0, 9).set(1, 8).get(1);

the return value is 8 (as set(1, 8) should overwrite the existing entry with value 2).
However, on Jurassic it returns 2.

MapInstance.Set() looks like the following:

    [JSInternalFunction(Name = "set")]
    public MapInstance Set(object key, object value)
    {
        if (this.store.ContainsKey(key))
            return this;
        if (key is double && TypeUtilities.IsNegativeZero((double)key))
            key = 0;
        var node = this.list.AddLast(new KeyValuePair<object, object>(key, value));
        this.store.Add(key, node);
        return this;
    }

So it checks whether the key already exists, but in that case does not set the new value.
ES2015 says at 23.1.3.9:

5. Repeat for each Record {[[key]], [[value]]} p that is an element of entries,
a. If p.[[key]] is not empty and SameValueZero(p.[[key]], key) is true, then
i. Set p.[[value]] to value.
ii. Return M.

So it seems the first if branch misses the code to set the new value.

Thanks!

[paulbartrum]

Fixed.