_getSpacesAndCommentsBeforeNode(node, i) {
    // List of start positions for nodes with spaces and comments:
    let positions = [];
    let sendPositions = false;

    for (let l = node.length; i < l; i++) {
      let currentNode = node.get(i);

      // If the node is declaration or @-rule, stop and return all
      // found nodes with spaces and comments (if there are any):
      if (!this._isSpaceOrComment(currentNode)) {
        sendPositions = true;
        break;
      }

      positions.push(i);
    }

    return sendPositions ? positions : null;
  }
Check if there are any comments or spaces before
the declaration/@-rule.
@param {Node} node
@param {Number} i
@returns {Array} List of nodes with spaces and comments