LayoutTests/css3/filters/effect-reference-ordering.html

<svg xmlns="http://www.w3.org/2000/svg" width="0" height="0" version="1.1">
  <defs>
    <filter id="blurX">
      <feGaussianBlur stdDeviation="5 0"/>
    </filter>
    <filter id="blurY">
      <feGaussianBlur stdDeviation="0 5"/>
    </filter>
  </defs>
</svg>
<style>
img {
    margin: 10px;
}
</style>
<img style="filter: url(#blurY);" src="resources/reference.png">
<img style="filter: contrast(500%) url(#blurY);" src="resources/reference.png">
<img style="filter: url(#blurY) contrast(500%);" src="resources/reference.png">
<img style="filter: url(#blurX) contrast(500%); url(#blurY);" src="resources/reference.png">