A Misconception About the JavaScript Prototype Chain中文EN

I used to be confused about prototype inheritance versus identifier lookup in the JavaScript prototype chain. Take this code:

function Foo() {};
var foo = new Foo();
Foo.prototype.label = "laruence";
alert(foo.label); //output: laruence
alert(Foo.label);//output: undefined

Today I came across this diagram:

Also, over at Javascript Object Hierarchy I read:

The prototype is only used for properties inherited by objects/instances created by that function. The function itself does not use the associated prototype.

In other words, the prototype of a function object plays no part in prototype chain lookup.
Today, under firefox (which exposes [[prototype]] through __proto__), I found that what actually takes part in identifier lookup is the __proto__ of the function object:

function Foo() {};
var foo = new Foo();
Foo.__proto__.label = "laruence";
alert(Foo.label); //output: laruence
alert(foo.label);//output: undefined

And, obviously:

function Foo() {};
alert(Foo.__proto__ === Foo.prototype); //output: false

It also explains this:

alert(Object.forEach); // undefined
Function.prototype.forEach = function(object, block, context) {
    for (var key in object) {
        if (typeof this.prototype[key] == "undefined") {
            block.call(context, object[key], key, object);
        }
    }
};
alert(Object.forEach);
alert(Function.forEach);
alert(Object.forEach === Function.forEach); // true