Add ts-loader dependency

[guybedford]

Somehow this one seems to have gotten missed.

[codecov-io]

Codecov Report

Merging #118 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #118   +/-   ##
=======================================
  Coverage   75.11%   75.11%           
=======================================
  Files          10       10           
  Lines         450      450           
=======================================
  Hits          338      338           
  Misses        112      112

---

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 8032a35...45cf962. Read the comment docs.