index.html

<!doctype html>
<head>
  <meta charset="utf-8">
  <title>Test Iframe</title>
  <style>
    iframe {
      height: 600px;
    }

   .static-text {
     display: inline-block;
   }

   iframe, .static-text {
     width: 350px;
   }
  </style>
  <script>
   'use strict';
   (function() {
     var div = document.createElement('DIV');
     var html = 'x<iframe src="resize-iframe.html"></iframe>';
     div.innerHTML = html;
     var ifr = div.lastChild;

     window.onload = function() {
       document.body.appendChild(ifr);
     };

   })();
  </script>
</head>
<span>
  Outer iframes src:
    <a href="resize-iframe.html" target="blank">resize-iframe.html</a>
</span>
<p>
  <span class="static-text">Static outer iframe</span>
  <span>Dinamic outer iframe</span>
</p>
<iframe src="resize-iframe.html"></iframe>