Allow --inspect-brk option to be used with babel-node [6.x backport]

[noinkling]

Backport of #5785

(first attempt was at #5795, sorry)

[mention-bot]

@noinkling, thanks for your PR! By analyzing the history of the files in this pull request, we identified @hzoo, @neVERberleRfellerER and @danez to be potential reviewers.

[codecov]

Codecov Report

Merging #5796 into master will increase coverage by 0.03%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #5796      +/-   ##
==========================================
+ Coverage   84.76%   84.79%   +0.03%     
==========================================
  Files         204      204              
  Lines        9607     9608       +1     
  Branches     2701     2702       +1     
==========================================
+ Hits         8143     8147       +4     
+ Misses        980      977       -3     
  Partials      484      484

Impacted Files	Coverage Δ
packages/babel-cli/src/babel-node.js	48.97% <0%> (-1.03%)	⬇️
...bel-plugin-transform-es2015-classes/src/vanilla.js	90.59% <0%> (+0.42%)	⬆️
packages/babel-traverse/src/path/context.js	86.2% <0%> (+0.86%)	⬆️
packages/babel-traverse/src/path/modification.js	74.75% <0%> (+0.97%)	⬆️
packages/babel-helper-call-delegate/src/index.js	68% <0%> (+4%)	⬆️

---

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 dcbb6c5...0230dc5. Read the comment docs.

[existentialism]

@noinkling thanks!