code: function setNodeOpacity_(node, op) {
    // closure compiler removed?
    op = Math.min(Math.max(op, 0), 1);
    if (node) {
      var st = node.style;
      if (typeof st.opacity !== 'undefined') {
        st.opacity = op;
      }
      if (typeof st.filters !== 'undefined') {
        st.filters.alpha.opacity = Math.floor(100 * op);
      }
      if (typeof st.filter !== 'undefined') {
        st.filter = "alpha(opacity:" + Math.floor(op * 100) + ")";
      }
    }
  }
docs: Set opacity of a node.
  @param {Node} node
  @param {Number} 0-1