Issue with stopping gifs in Chrome 49

If you close the alert and image is already cached (?), an animation of gif will not start. To start animation you can select text or resize viewport.

by SerGen

HTML

<button id="btn">Show GIF!</button>
<img hidden src="data:image/gif;base64,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" alt="" id="img">

CSS

/*
Issue with stopping gifs in Chrome 49

If you close the alert and image is already cached (?), an animation of gif will not start.
To start animation you can select text or resize viewport.
*/

JavaScript

btn.onclick = function () {
    img.removeAttribute('hidden');
    alert('Animation shall not pass!');
};