docs: void pushActiveFormattingElements(Element in) {
          int numSeen = 0;
          for (int pos = formattingElements.size() -1; pos >= 0; pos--) {
              Element el = formattingElements.get(pos);
              if (el == null) // marker
                  break;
  
              if (isSameFormattingElement(in, el))
                  numSeen++;
  
              if (numSeen == 3) {
                  formattingElements.remove(pos);
                  break;
              }
          }
          formattingElements.add(in);
      }