blank-object

Object.create(null) turns out to be quite slow to alloc in v8, but instead if
we inherit from an ancestory with proto = create(null) we have nearly
the same functionallity but with dramatically faster alloc.

``js
var BlankObject = require('blank-object');

var bo = new BlankObject();
`

This is designed for a presence check map[key] !== undefined since in is also slow like hasOwnProperty, delete and Object.create.

`js
function UNDEFINED() {}
export default class Map {
constructor() {
this.store = new BlankObject();
}

has(key) {
return this.store[key] !== undefined;
}

get(key) {
let val = this.store[key];
return val === UNDEFINED ? undefined : val;
}

set(key, val) {
this.store[key] = val === undefined ? UNDEFINED : val;
}
}
``