code: function removeUnUseDecl(decl, toRemovePropName) {
      let nodes = decl.parent.nodes;
      let currIdx = nodes.indexOf(decl);
  
      for (let i = currIdx - 1; i >= 0; i--) {
          let item = nodes[i];
          if (item.type === 'decl' && item.prop === toRemovePropName) {
              item.remove();
          }
      }
  }
docs: Remove the given property name style declaration that the position is
  front of the current given style declaration.
  
  @inner
  @param {Object} decl the style property declaration that will override
  the front of the style declaration that has the same property name
  @param {string} toRemovePropName the property name to remove