message: fix(Field): disabled label color
diff: @import '../style/var';
  .van-field {
  - &--disabled {
  - color: @field-disabled-text-color;
  - }
  -
  &__label {
  flex: none;
  box-sizing: border-box;
  }
  }
  + &--disabled {
  + .van-field__label {
  + color: @field-disabled-text-color;
  + }
  + }
  +
  &__value {
  overflow: visible;
  }
  