third_party/WebKit/LayoutTests/fast/canvas/webgl/resources/imageBitmap-transferable.js

self.onmessage = function(e) {
    createImageBitmap(e.data, {imageOrientation: "none", premultiplyAlpha: "none"}).then(imageBitmap => {
        postMessage(imageBitmap, [imageBitmap]);
    });
};