gistfile1.js

window.requestAnimationFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;

if (isAnimationSupported()) {
    //Create CssAnimationClass and play
} else {
    //Fallback to js animations
    requestAnimationFrame(animateCarouselBubbleIn)
}

var start = null;

function animateCarouselBubbleIn(timestamp) {
    var progress;
    if (start === null) {
        start = timestamp;
    }
    progress = Math.min((timestamp - start) / 600, 1); //Percent progress
    bubbleEl.style.left = (1 - progress) * -150 + "%";
    bubbleEl.style.top = (1 - progress) * 25 + "%";
    bubbleEl.style.height = .9 * (progress * origHeight) + .1 * origHeight + "%" //Add .1 since the CSS3 animation starts from scale .1
    bubbleEl.style.width = .9 * (progress * origWidth) + .1 * origHeight + "%"
    if (progress < 1) {
        requestAnimationFrame(animateCarouselBubbleIn);
    }
}