chromium/third_party/blink/web_tests/fast/frames/frame-set-scaling.html

<html><head><title>Frame Scale Test</title></head>
  <frameset style="background-color: red; -webkit-transform-origin: 0% 0%; transform:  scale(0.5, 0.5);" cols="30%,*">
    <frame src="data:text/html,<body bgcolor='green'></body>">
    <frame src="data:text/html,<body bgcolor='green'></body>">
  </frameset>
</html>