<svg xmlns="http://www.w3.org/2000/svg"
     onload="
        document.documentElement.pauseAnimations();
        document.documentElement.setCurrentTime(0);
        document.getElementById('b').removeAttribute('begin');
        document.getElementById('a').setAttribute('dur', '1s')">
  <rect>
    <animate attributeName="y" attributeType="XML" id="a"/>
    <animate attributeName="fill" attributeType="CSS" id="b"
      begin="a.end" dur="2s"/>
  </rect>
</svg>