Pass SIGINT signals to the spawned child process

[bill-improbableio]

Q	A
Patch: Bug Fix?	yes
Major: Breaking Change?	no
Minor: New Feature?	no
Deprecations?	no
Spec Compliancy?	yes (?)
Tests Added/Pass?	yes
Fixed Tickets	Fixes #1062
License	MIT
Doc PR	no
Dependency Changes	no

Fixes an issue where SIGINT was not passed to the running child process when a script was started using babel-node.

NOTE: this issue does not manifest if kexec is installed as a dependency.

See #1062

[codecov]

Codecov Report

Merging #5861 into 7.0 will increase coverage by <.01%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##              7.0    #5861      +/-   ##
==========================================
+ Coverage   85.25%   85.25%   +<.01%     
==========================================
  Files         284      284              
  Lines        9963     9966       +3     
  Branches     2781     2781              
==========================================
+ Hits         8494     8497       +3     
  Misses        969      969              
  Partials      500      500

Impacted Files	Coverage Δ
packages/babel-cli/src/babel-node.js	46% <33.33%> (-0.81%)	⬇️
packages/babel-traverse/src/path/context.js	86.2% <0%> (ø)	⬆️
...bel-plugin-transform-es2015-classes/src/vanilla.js	91.06% <0%> (+0.42%)	⬆️
packages/babel-traverse/src/visitors.js	86.66% <0%> (+0.95%)	⬆️

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[hzoo]

Oh, now I wonder why it's not a dependency then, or was it meant to be optional?

[jridgewell]

kexec can't be installed on all systems.

[oliviertassinari]

Side note: this logic is no longer present in v7.x.

[davidfraser]

@oliviertassinari is right - src/babel-node.js was moved from packages/babel-cli to packages/babel-node by @existentialism in 6d965c0 (see #6023), but lost this code, which was still present when it was removed from packages/babel-cli in 2374062 (see src/babel-node.js#L103)

[existentialism]

@oliviertassinari @davidfraser thanks, opened #7511!