message: CustomSelect: simplify border-radius override
diff: }
  .CustomSelect__open .FormField__border {
  - border-radius: 8px 8px 0 0;
  + border-bottom-left-radius: 0;
  + border-bottom-right-radius: 0;
  }
  .CustomSelect__open--popupDirectionTop .FormField__border {
  - border-radius: 0 0 8px 8px;
  -}
  -
  -/**
  - * iOS
  - */
  -
  -.CustomSelect--ios .CustomSelect__open .FormField__border {
  - border-radius: 10px 10px 0 0;
  -}
  -
  -.CustomSelect--ios .CustomSelect__open--popupDirectionTop .FormField__border {
  - border-radius: 0 0 10px 10px;
  -}
  -
  -@media (min-resolution: 2dppx) {
  - .CustomSelect--ios .CustomSelect__open .FormField__border {
  - border-radius: 20px 20px 0 0;
  - }
  -
  - .CustomSelect--ios .CustomSelect__open--popupDirectionTop .FormField__border {
  - border-radius: 0 0 20px 20px;
  - }
  -}
  -
  -@media (min-resolution: 3dppx) {
  - .CustomSelect--ios .CustomSelect__open .FormField__border {
  - border-radius: 31.25px 31.25px 0 0;
  - }
  -
  - .CustomSelect--ios .CustomSelect__open--popupDirectionTop .FormField__border {
  - border-radius: 0 0 31.25px 31.25px;
  - }
  -}
  -
  -/**
  - * VKCOM
  - */
  -.CustomSelect--vkcom .CustomSelect__open .FormField__border {
  - border-radius: 6px 6px 0 0;
  -}
  -
  -.CustomSelect--vkcom .CustomSelect__open--popupDirectionTop .FormField__border {
  - border-radius: 0 0 6px 6px;
  + border-top-left-radius: 0;
  + border-top-right-radius: 0;
  }
  