message: style(Popup): use animation timing function less var
diff: &-slide-left-enter-active,
  &-slide-right-enter-active,
  &-slide-bottom-enter-active {
  - transition-timing-function: ease-out;
  + transition-timing-function: @animation-timing-function-enter;
  }
  &-slide-top-leave-active,
  &-slide-left-leave-active,
  &-slide-right-leave-active,
  &-slide-bottom-leave-active {
  - transition-timing-function: ease-in;
  + transition-timing-function: @animation-timing-function-leave;
  }
  &-slide-top-enter,
  