-webkit-box-orient is lost when generating css file

[MathieuMarchant]

Describe the bug
To have a multi-line overflow with ellipsis, I'm using the "-webkit-box-orient" style on the p tag.
However on generation this line is not taken into account.

Other "-webkit-line-clamp" is taken into account.

To Reproduce
Create a less file and add the following

p {
            display: -webkit-box;
            -webkit-line-clamp: 2;
            -webkit-box-orient: vertical;
            overflow: hidden;
            text-overflow: ellipsis;
        }

Compile the less file and generate into CSS. The generated CSS looks like this:

p {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  overflow: hidden;
  text-overflow: ellipsis;
}

You can see the box-orient is dropped.

Expected behavior
The generated code should have the box orient in there.