LayoutTests/wasm/window-postmessage.html

<!DOCTYPE html>
<script src="../resources/js-test.js"></script>
<script src="../resources/wasm-builder.js"></script>
<script src="./resources/load_wasm.js"></script>
<script>
description("Test that expected Wasm Module can be sent over window.postMessage.");
if (window.testRunner)
    testRunner.waitUntilDone();

window.addEventListener("message", (answer) => finish(answer.data), false);

function finish(module) {
    var i = new WebAssembly.Instance(module);
    var value = i.exports.calc(1);
    shouldBe(() => value, () => 7002);

    if (window.testRunner)
        testRunner.notifyDone();
}

var run = async function () {
    try {
        var mod = await createWasmModule();
        window.postMessage(mod, '*');
    } catch (e) {
        console.log('error:', e);
    }
};

setTimeout(run);
</script>