Codebase Browser
chromium
Go to App

chromium/third_party/blink/web_tests/external/wpt/html/editing/dnd/platform/drag-keypress-manual.html 

<!DOCTYPE html>
<title>drag &amp; drop - pressing tab while dragging</title>
<style>
  body > div {
    height: 200px;
    width: 200px;
    background-color: orange;
  }
  body {
    height: 5000px;
  }
  p {
    margin-top: 1000px;
  }
</style>

<script>
window.onload = function() {
  window.scrollBy(0,1000);
  document.getElementsByTagName('div')[0].ondragstart = function(e) {
    e.dataTransfer.effectAllowed = 'copy';
    e.dataTransfer.setData('text', 'dummy text');
  };
};
</script>
<noscript>Enable JavaScript and reload</noscript>
<p>Drag the orange square. While still dragging, press the Tab key on your keyboard. Fail if the page scrolls.</p>
<div draggable="true"></div>