Add has and delete methods to WeakMap

[thoov]

No description provided.

[stefanpenner]

What if the value being stored is false or 0

I think the trick will be to do this.get(obj) !== 'undefined' an dif someone tries to set undefined we insert a sentinel value.

Example of such a sentinel: https://github.com/emberjs/ember.js/blob/master/packages/ember-metal/lib/cache.js#L13

https://github.com/emberjs/ember.js/blob/master/packages/ember-metal/lib/cache.js#L13

this prevents a potentially costly in check...

[thoov]

@stefanpenner fixed

[thoov]

Also added check for keys that are not objects when setting

[stefanpenner]

value === undefined is what we want here. (perfs)

[thoov]

good catch. I updated

[stefanpenner]

lets do function UNDEFINED() {} that way it is named nicely in most modern debuggers.

[thoov]

good call. updated

[stefanpenner]

thanks :)