Quelle  call.js

// |reftest| skip-if(!this.hasOwnProperty("Intl"))

function IsIntlService(c) {
    return typeof c === "function" &&
           c.hasOwnProperty("prototype") &&
           c.prototype.hasOwnProperty("resolvedOptions");
}

function IsObject(o) {
    return Object(o) === o;
}

function thisValues() {
    const intlConstructors = Object.getOwnPropertyNames(Intl).map(name => Intl[name]).filter(IsIntlService);

    return [
        // Primitive values.
        ...[undefined, null, true, "abc", Symbol(), 123],

        // Object values.
        ...[{}, [], /(?:)/, function(){}, new Proxy({}, {})],

        // Intl objects.
        ...[].concat(...intlConstructors.map(ctor => {
            let args = [];
            if (ctor === Intl.DisplayNames) {
                // Intl.DisplayNames can't be constructed without any arguments.
                args = [undefined, {type: "language"}];
            }

            return [
                // Instance of an Intl constructor.
                new ctor(...args),

                // Instance of a subclassed Intl constructor.
                new class extends ctor {}(...args),

                // Object inheriting from an Intl constructor prototype.
                Object.create(ctor.prototype),

                // Intl object not inheriting from its default prototype.
                Object.setPrototypeOf(new ctor(...args), Object.prototype),
            ];
        })),
    ];
}

// Invoking [[Call]] for Intl.Collator always returns a new Collator instance.
for (let thisValue of thisValues()) {
    let obj = Intl.Collator.call(thisValue);
    assertEq(Object.is(obj, thisValue), false);
    assertEq(obj instanceof Intl.Collator, true);

    // Ensure Intl.[[FallbackSymbol]] wasn't installed on |thisValue|.
    if (IsObject(thisValue))
        assertEqArray(Object.getOwnPropertySymbols(thisValue), []);
}

// Intl.Collator doesn't use the legacy Intl constructor compromise semantics.
for (let thisValue of thisValues()) {
    // Ensure instanceof operator isn't invoked for Intl.Collator.
    Object.defineProperty(Intl.Collator, Symbol.hasInstance, {
        get() {
            assertEq(false, true, "@@hasInstance operator called");
        }, configurable: true
    });
    let obj = Intl.Collator.call(thisValue);
    delete Intl.Collator[Symbol.hasInstance];
    assertEq(Object.is(obj, thisValue), false);
    assertEq(obj instanceof Intl.Collator, true);
}

if (typeof reportCompare === "function")
    reportCompare(true, true);