Remove variables support - theme variants

[tomdye]

Description:

Removes special rules for variables.css files.

Work towards: dojo/framework#683

[codecov]

Codecov Report

Merging #35 into master will not change coverage by %.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master     #35   +/-   ##
======================================
  Coverage    0.00%   0.00%           
======================================
  Files           5       5           
  Lines         159     157    -2     
  Branches       20      20           
======================================
+ Misses        159     157    -2     

Impacted Files	Coverage Δ
src/webpack.config.ts	0.00% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b46aee3...44ce7c6. Read the comment docs.