kingElement, element);

        if (scrollLocked) {
          this._lockedElementCache.push(element);
        } else {
          this._unlockedElementCache.push(element);
        }

        return scrollLocked;
      },

      /**
       * Push an element onto the current scroll lock stack. The most recently
       * pushed element and its children will be considered scrollable. All
       * other elements will not be scrollable.
       *
       * Scroll locking is implemented as a stack so that cases such 