function warnIfGridRowColumnExists(decl, result) {
  let rule = decl.parent
  let decls = []
  rule.walkDecls(/^grid-(row|column)/, d => {
    if (
      !d.prop.endsWith('-end') &&
      !d.value.startsWith('span') &&
      !d.prop.endsWith('-gap')
    ) {
      decls.push(d)
    }
  })
  if (decls.length > 0) {
    decls.forEach(d => {
      d.warn(
        result,
        'You already have a grid-area declaration present in the rule. ' +
          `You should use either grid-area or ${d.prop}, not both`
      )
    })
  }

  return undefined
}
warn user if both grid-area and grid-(row|column)
declarations are present in the same rule
@param  {Declaration} decl
@param  {Result} result
@return {void}