function processUnscopedStyle(style) {
  const text = style.textContent;
  if (!styleTextSet.has(text)) {
    styleTextSet.add(text);
    const newStyle = style.cloneNode(true);
    document.head.appendChild(newStyle);
  }
}
Add a specifically-marked style to the document directly, and only one copy of that style.

@param {!HTMLStyleElement} style
@return {undefined}