chromium/third_party/blink/renderer/core/testing/data/long_press_link_in_iframe.html

<html>
<head>
 <script>
   function onLoad() {
    var iframeDocument = document.getElementById("childframe").contentDocument;
     iframeDocument.body.innerHTML = "<div><a id='anchorTag' href='http://www.example.com' style='position: absolute; left: 20px; top: 20px; height: 20px;'>Link to example.com</a></div>";
    var anchor = iframeDocument.getElementById("anchorTag");
    anchor.addEventListener("contextmenu", function(event) { document.title = "anchor contextmenu"; });
  }
</script>
</head>
<body onload="onLoad()">
  <iframe id="childframe" style="width: 100px; height: 100px;"></iframe>
</body>
<html>