chromium/src/third_party/blink/web_tests/fast/canvas/canvas-after-detachment.html

<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<div id="parent">
<canvas id="mycanvas" width="200" height="200"></canvas>
<script>
test(function(t) {
    var parent = document.getElementById("parent");
    var canvas = document.getElementById('mycanvas');
    var ctx = canvas.getContext('2d');
    ctx.fillStyle = 'red';
    ctx.fillRect(0, 0, 200, 200);

    var imageData;
    imageData = ctx.getImageData(100, 100, 1, 1);
    var data = imageData.data;
    assert_equals(data[0], 255);
    assert_equals(data[1], 0);
    assert_equals(data[2], 0);

    parent.removeChild(canvas);
    // GC makes sure canvas element is removed.
    if (window.GCController)
        GCController.collect();

    imageData = ctx.getImageData(100, 100, 1, 1);
    data = imageData.data;
    assert_equals(data[0], 255);
    assert_equals(data[1], 0);
    assert_equals(data[2], 0);
}, 'Test that the context is valid although the canvas is detached from document.');
</script>