Do not extend Array.prototype

[neumino]

Instead of saving things in this.__proto__ when we send back an array, I'm changing the internal prototype after the objects are created.
That way, we keep all the usual checks valid for Arrays.

Review 1326 assigned to @AtnNn
Branch michel_arrayresult

michel@T520:~$ node
> a = [1,2,3]
[ 1, 2, 3 ]
> a.__proto__ = {}
{}
> a.__proto__["toArray"] = function() { return this.slice(0, this.length) }
[Function]
> a.__proto__.__proto__ = [].__proto__
[]
> a
[ 1, 2, 3 ]
> a.toArray()
[ 1, 2, 3 ]
> a instanceof Array
true
> Object.prototype.toString.call(a)
'[object Array]'
> a.constructor
[Function: Array]

[coffeemug]

Moving to polish. I think we should have a stricter rule to only keep issues in 1.12 if we're willing to hold the release for them.

[neumino]

Merged in next as f9c0e52
Ship 1.12