Avoid substitutions when Webpack was introduced

[w89612b]

Avoid 'require' being replaced with Webpack's unique declaration 'non_webpack_require' when Webpack introduces packaging

Issue #, if available:

Description of changes:

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[codecov]

Codecov Report

Merging #4476 (0af8b48) into master (554831e) will not change coverage.
The diff coverage is 33.33%.

@@           Coverage Diff           @@
##           master    #4476   +/-   ##
=======================================
  Coverage   70.55%   70.55%           
=======================================
  Files         543      543           
  Lines       54238    54238           
  Branches    10186    10186           
=======================================
  Hits        38268    38268           
  Misses      15970    15970           

Flag	Coverage Δ
unittests	70.55% <33.33%> (ø)

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Impacted Files	Coverage Δ
lib/ace/worker/worker.js	50.00% <33.33%> (ø)

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