Update babel to 7.11.6.

[legander]

Update babel from [6.26.0, preset=latest] to [7.11.6, preset=env].

• Improving transpile time quite significantly for large scripts.
• Needs some testing to ensure same level of ES feature support as previous build.

[CLAassistant]

All committers have signed the CLA.

[codecov-io]

Codecov Report

Merging #1663 into master will decrease coverage by 0.04%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1663      +/-   ##
==========================================
- Coverage   72.15%   72.10%   -0.05%     
==========================================
  Files         166      167       +1     
  Lines       12787    12884      +97     
==========================================
+ Hits         9226     9290      +64     
- Misses       3011     3030      +19     
- Partials      550      564      +14     

Flag	Coverage Δ
#ubuntu	72.06% <0.00%> (?)
#windows	70.58% <0.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
js/compiler/compiler.go	73.58% <0.00%> (-2.89%)	⬇️
js/compiler/rice-box.go	100.00% <ø> (ø)
stats/statsd/collector.go	65.21% <0.00%> (-34.79%)	⬇️
stats/datadog/collector.go	74.19% <0.00%> (-25.81%)	⬇️
cmd/options.go	61.43% <0.00%> (-1.76%)	⬇️
cmd/collectors.go	0.00% <0.00%> (ø)
lib/netext/httpext/response.go	91.11% <0.00%> (ø)
stats/statsd/common/collector.go	81.92% <0.00%> (ø)
stats/statsd/common/config.go
... and 14 more

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[na--]

With the latest changes in goja (native support block-scoped variables, added in dop251/goja#264 and adopted in #1904), we are probably not going to update babel soon - we no longer have issues with k6 archive taking forever on long scripts... So I'll close this issue, cc @sniku.

In any case, if we want to update babel, we'll definitely need another PR, because:

• we have to take the TC39 tests that we now have into account, we added them in the k6 CI, after this PR was submitted (Add tc39/test262 tests in k6 #1747)
• we'll likely not use go.rice to embed the file, we want to get rid of that dependency (k6 dependencies update policy discussion #1933) and use the native Go file embedding , since that way we won't have 2 copies of the file in the git repo
• we'd probably want to use the newest Babel version and we might have to adjust the preset