Stylesheet parsing error

Empty values in the stylesheet broke the tokenizing process, e.g. on:

text-shadow: none /*{a-bar-shadow-x}*/  /*{a-bar-shadow-y}*/  /*{a-bar-shadow-radius}*/  /*{a-bar-shadow-color}*/;

This created incorrect tokens like:

a-bar-shadow-x}*/  /*{a-bar-shadow-y"

This resulted in corrupt swatches.

Signed-off-by: ucavus <ucavus@github.fake>