chromium/third_party/blink/web_tests/images/huge-image-viewport-scale.html

<!DOCTYPE html>
<script src="../resources/run-after-layout-and-paint.js"></script>
<script>
if (window.testRunner) {
  testRunner.dumpAsText();
  testRunner.setPopupBlockingEnabled(false);
  testRunner.waitUntilDone();
}

onload = function() {
  var newWindow = window.open('resources/5000x5000.png', 'image', 'width=100,height=150');
  newWindow.onload = function() {
    if (newWindow.internals)
      newWindow.internals.settings.setViewportEnabled(true);
    runAfterLayoutAndPaint(function() {
      document.getElementById('output').textContent =
          '\nviewport meta: ' + newWindow.document.querySelector('meta').outerHTML
          + '\nimage style: ' + newWindow.document.querySelector('img').getAttribute('style')
          + '\nimage actual width: ' + newWindow.document.querySelector('img').offsetWidth;
      if (window.testRunner)
        testRunner.notifyDone();
    });
  };
}
</script>
Tests huge image scaling when viewport is enabled. Requires DumpRenderTree.<br>
To manual test, open resources/5000x5000.png in a viewport-capable browser (e.g. on Android or enable viewport emulation in DevTools).<br>
Passes if the image shinks to fit the width.<br>
<pre id="output"></pre>