<svg xmlns="http://www.w3.org/2000/svg">
<clipPath id="clip1">
  <rect width="400" height="400" style="-webkit-transform: scale(.5); transform: scale(.5)"/>
  <!-- Second rect may causes masking. -->
  <rect width="400" height="400" style="-webkit-transform: scale(.5); transform: scale(.5)"/>
</clipPath>
<rect width="400" height="400" fill="red" clip-path="url(#clip1)"/>
<rect width="200" height="200" fill="green"/>
</svg>