`isAllowedKey` / `isConstructorPrototype` / `throwOnProto` logic is unnecessary and harmful

[zloirock]

A superset of #1.

parseJson('{ "__proto__": 1 }'); // => {}
parseJson('{ "constructor": { "prototype": 1 } }'); // => { constructor: {} }

and SyntaxError with throwOnProto,

when native

JSON.parse('{ "__proto__": 1 }'); // => { __proto__: 1 }
JSON.parse('{ "constructor": { "prototype": 1 } }'); // => { constructor: { prototype: 1 } }

It's absolutely nothing dangerous in constructor: prototype in object literal.

__proto__ and custom Object.prototype getters can be worked around via Object.defineProperty:

      if (key in Object.prototype) {
        Object.defineProperty(object, key, {
          value: result.value,
          enumerable: true,
          writable: true,
          configurable: true
        });
      } else object[key] = result.value;