function childHandler(child) {
    // TODO(user): More coercion, ala MochiKit?
    if (child) {
      parent.appendChild(
          typeof child === 'string' ? doc.createTextNode(child) : child);
    }
  }
Appends a node with text or other nodes.
@param {!Document} doc The document to create new nodes in.
@param {!Node} parent The node to append nodes to.
@param {!Arguments} args The values to add. See `goog.dom.append`.
@param {number} startIndex The index of the array to start from.
@private