Eliminating unused classes #127

Let's say I have the following code:

/* test.css */

.roundedBorder {
  border-radius: 5px;
}

.redBorder {
  border: 1px solid red;
}

.roundedAndRedBorder {
  composes: roundedBorder;
  composes: redBorder;
}

/* test.js */
import styles from './test.css'

console.log(styles)

When I run the code with style loader and css loader, the output is:

{
  "roundedBorder": "test__roundedBorder",
  "redBorder": "test__redBorder",
  "roundedAndRedBorder": "test__roundedAndRedBorder test__roundedBorder test__redBorder"
}

and the style element added into DOM is:

<style type="text/css">
.test__roundedBorder {
  border-radius: 5px;
}

.test__redBorder {
  border: 1px solid red;
}

.test__roundedAndRedBorder {
}
</style>

The class roundedAndRedBorder is used here only to compose the two other classes. Therefore, I think we should not have the class test__roundedAndRedBorder in the output. What do you think?