moveToBottomSelectedElem = () => {
  const [selected] = svgCanvas.getSelectedElements()
  if (selected) {
    let t = selected
    const oldParent = t.parentNode
    const oldNextSibling = t.nextSibling
    let { firstChild } = t.parentNode
    if (firstChild.tagName === 'title') {
      firstChild = firstChild.nextSibling
    }
    // This can probably be removed, as the defs should not ever apppear
    // inside a layer group
    if (firstChild.tagName === 'defs') {
      firstChild = firstChild.nextSibling
    }
    t = t.parentNode.insertBefore(t, firstChild)
    // If the element actually moved position, add the command and fire the changed
    // event handler.
    if (oldNextSibling !== t.nextSibling) {
      svgCanvas.addCommandToHistory(
        new MoveElementCommand(t, oldNextSibling, oldParent, 'bottom')
      )
      svgCanvas.call('changed', [t])
    }
  }
}
Repositions the selected element to the top in the DOM to appear under
other elements.
@function module:selected-elem.SvgCanvas#moveToBottomSelectedElement
@fires module:selected-elem.SvgCanvas#event:changed
@returns {void}