How to convert nested setTimeouts to promises

Using rsvp.js or any other promises/A+ implementation how can I turn code like...

console.log('step 1');
setTimeout(function() {
  console.log('step 2');
  setTimeout(function() {
    console.log('step 3');
  }, 100);
}, 300);

into a promises implementation?

Create a delay function which returns a Promise and it actually resolves it after the specified time elapses in setTimeout, like this

function delay(time) {
    return new RSVP.Promise(function (resolve) {
        setTimeout(resolve, time);
    });
}

and then you can invoke it like this

console.log("step 1");
delay(3000)
    .then(function () {
        console.log("step 2");
        return delay(1000);
    })
    .then(function () {
        console.log("step 3");
    });