__proto__ vs usable Object.create() wrapper

__proto__.js

var c = 100e3;

var proto = {
	a: 0,
	b: {},
	c: [],
	d: function() {},
	e: /./
};

var i = c + 1, t = performance.now();
while(--i) {
	var o = inherit(proto, {
		f: true,
		g: "test",
		h: function() {}
	});
}
var dt1 = performance.now() - t;

var i = c + 1, t = performance.now();
while(--i) {
	var o = {
		__proto__: proto,
		f: true,
		g: "test",
		h: function() {}
	};
}
var dt2 = performance.now() - t;

var i = c + 1, t = performance.now();
while(--i) {
	var o = ensurePrototype({
		__proto__: proto,
		f: true,
		g: "test",
		h: function() {}
	});
}
var dt3 = performance.now() - t;

var i = c + 1, t = performance.now();
while(--i) {
	var o = ensurePrototype$({
		__proto__$: proto,
		f: true,
		g: "test",
		h: function() {}
	});
}
var dt4 = performance.now() - t;

alert(
	"inherit(): " + dt1.toFixed(2) + " ms\n" +
	"__proto__: " + dt2.toFixed(2) + " ms\n" +
	"ensurePrototype(): " + dt3.toFixed(2) + " ms\n" +
	"ensurePrototype() w/o __proto__: " + dt4.toFixed(2) + " ms"
);


// https://github.com/piroor/fxaddonlib-inherit
function toPropertyDescriptors(aProperties) {
	var descriptors = {};
	Object.keys(aProperties).forEach(function(aProperty) {
		var description = Object.getOwnPropertyDescriptor(aProperties, aProperty);
		descriptors[aProperty] = description;
	});
	return descriptors;
}

function inherit(aParent, aExtraProperties) {
	var global;
	if (Components.utils.getGlobalForObject)
		global = Components.utils.getGlobalForObject(aParent);
	else
		global = aParent.valueOf.call();
	global = global || this;

	var ObjectClass = global.Object || Object;

	if (!ObjectClass.create) {
		aExtraProperties = aExtraProperties || new ObjectClass;
		aExtraProperties.__proto__ = aParent;
		return aExtraProperties;
	}
	if (aExtraProperties)
		return ObjectClass.create(aParent, toPropertyDescriptors(aExtraProperties));
	else
		return ObjectClass.create(aParent);
}


function ensurePrototype(o) {
	ensurePrototype = "hasOwnProperty" in ({ __proto__: null })
		? function(o) {
			var proto = o.__proto__;
			delete o.__proto__;

			var global;
			if(Components.utils.getGlobalForObject)
				global = Components.utils.getGlobalForObject(o);
			else
				global = o.valueOf.call();
			if(!global)
				global = this;
			var ObjectClass = global.Object || Object;

			var descs = {};
			Object.keys(o).forEach(function(p) {
				descs[p] = Object.getOwnPropertyDescriptor(o, p);
			});

			return ObjectClass.create(proto, descs);
		}
		: function(o) {
			return o;
		};
	return ensurePrototype(o);
}
function ensurePrototype$(o) { // To test performance w/o __proto__ support
	ensurePrototype$ = "hasOwnProperty" in ({ __proto__$: null })
		? function(o) {
			var proto = o.__proto__$;
			delete o.__proto__$;

			var global;
			if(Components.utils.getGlobalForObject)
				global = Components.utils.getGlobalForObject(o);
			else
				global = o.valueOf.call();
			if(!global)
				global = this;
			var ObjectClass = global.Object || Object;

			var descs = {};
			Object.keys(o).forEach(function(p) {
				descs[p] = Object.getOwnPropertyDescriptor(o, p);
			});

			return ObjectClass.create(proto, descs);
		}
		: function(o) {
			return o;
		};
	return ensurePrototype$(o);
}

For me (Firefox 29.0.1):

inherit(): 2246.00 ms
__proto__: 187.00 ms
ensurePrototype(): 203.00 ms
ensurePrototype() w/o __proto__: 2434.00 ms

:(

Also opened piroor/fxaddonlib-inherit#2