Be able to type -- after value to set unitless value for property

Currently when setting any value you can type the unit (e.g. px, em, rem %) directly after the value and this correctly changes the unit for that property.

The exception to this is for unitless values (e.g. 0 or if specifying a unitless line-height for example).

Ideally this will work by type a single or double dash after the value.

Hopefully this is a straightforward addition and will aid in consistency and completeness, thank you for considering it.