fix(demos): Re-enable JS source maps

[acdvorak]

No description provided.

[codecov-io]

Codecov Report

Merging #2124 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2124   +/-   ##
=======================================
  Coverage   99.43%   99.43%           
=======================================
  Files          84       84           
  Lines        3723     3723           
  Branches      486      486           
=======================================
  Hits         3702     3702           
  Misses         21       21

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[kfranqueiro]

LGTM, with expectation that we can probably remove one or more other variables that are mostly meaningless now.