Add global as in nodejs for backwards compatibility

[mstoykov]

this is only being added to the "extented" compatibility-mode as it was
being provided by core-js before it was dropped.

[imiric]

Can you add a small test for it?

[codecov-io]

Codecov Report

Merging #1845 (b3214e4) into master (c6dec36) will decrease coverage by 1.46%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1845      +/-   ##
==========================================
- Coverage   71.60%   70.13%   -1.47%     
==========================================
  Files         179      178       -1     
  Lines       13928    13929       +1     
==========================================
- Hits         9973     9769     -204     
- Misses       3323     3524     +201     
- Partials      632      636       +4     

Flag	Coverage Δ
ubuntu	?
windows	70.13% <100.00%> (+0.01%)	⬆️

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

Impacted Files	Coverage Δ
js/bundle.go	91.94% <100.00%> (+0.10%)	⬆️
js/modules/k6/http/cookiejar.go	15.00% <0.00%> (-55.00%)	⬇️
lib/netext/tls.go	18.00% <0.00%> (-30.00%)	⬇️
lib/testutils/httpmultibin/httpmultibin.go	66.29% <0.00%> (-23.60%)	⬇️
js/modules/k6/http/request.go	59.21% <0.00%> (-20.93%)	⬇️
loader/readsource.go	65.38% <0.00%> (-19.24%)	⬇️
lib/netext/httpext/request.go	82.53% <0.00%> (-14.46%)	⬇️
js/modules/k6/http/http_url.go	75.00% <0.00%> (-12.50%)	⬇️
lib/netext/httpext/digest_transport.go	68.42% <0.00%> (-10.53%)	⬇️
stats/statsd/common/collector.go	73.49% <0.00%> (-8.44%)	⬇️
... and 9 more

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