function hasInvalidModifiers(vSlot, allowModifiers) {
  return allowModifiers
    ? vSlot.key.argument == null && vSlot.key.modifiers.length > 0
    : vSlot.key.modifiers.length > 0
}
If `allowModifiers` option is set to `true`, check whether a given argument node has invalid modifiers like `v-slot.foo`.
Otherwise, check whether a given argument node has at least one modifier.
@param {VDirective} vSlot The `v-slot` directive to check.
@param {boolean} allowModifiers `allowModifiers` option in context.
@return {boolean} `true` if that argument node has invalid modifiers like `v-slot.foo`.