Update webpack4 lib + CLI.

[ryan-roemer]

• Updates to modern webpack4.
• Remove test/fixtures/packages/webpack4 hacks now that we only test on node8+.
• Now that we have a more modern webpack4, the stats objects for foo/green.js in prod are different because it's correctly not included in asset output. Add test patches to adjust tests, etc. Fixes #77

[codecov[bot]]

Codecov Report

Merging #115 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #115   +/-   ##
=======================================
  Coverage   90.58%   90.58%           
=======================================
  Files          15       15           
  Lines         765      765           
  Branches      124      124           
=======================================
  Hits          693      693           
  Misses         41       41           
  Partials       31       31

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Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 50b6c6c...4295c5e. Read the comment docs.

[codecov[bot]]

Codecov Report

Merging #115 into master will increase coverage by 0.25%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #115      +/-   ##
==========================================
+ Coverage   90.58%   90.84%   +0.25%     
==========================================
  Files          15       13       -2     
  Lines         765      732      -33     
  Branches      124      122       -2     
==========================================
- Hits          693      665      -28     
+ Misses         41       36       -5     
  Partials       31       31

Impacted Files	Coverage Δ
src/lib/util/files.ts	86.66% <0%> (-4.64%)	:arrow_down:
src/lib/util/strings.ts	100% <0%> (ø)	:arrow_up:
src/lib/util/promise.ts	100% <0%> (ø)	:arrow_up:
src/lib/index.ts
src/lib/interfaces/modules.ts
src/lib/actions.ts	100% <0%> (+33.33%)	:arrow_up:

---

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 50b6c6c...4295c5e. Read the comment docs.