fix: ensure compatibility with TS 3.7

[domoritz]

Needed for jupyterlab/jupyterlab#7428.

cc @jasongrout

[codecov]

Codecov Report

Merging #5497 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5497   +/-   ##
=======================================
  Coverage   96.29%   96.29%           
=======================================
  Files         161      161           
  Lines        8439     8439           
  Branches     2269     2269           
=======================================
  Hits         8126     8126           
  Misses        241      241           
  Partials       72       72

Impacted Files	Coverage Δ
src/spec/facet.ts	100% <ø> (ø)	⬆️
src/spec/repeat.ts	100% <ø> (ø)	⬆️
src/transform.ts	100% <ø> (ø)	⬆️
src/bin.ts	100% <ø> (ø)	⬆️
src/projection.ts	100% <ø> (ø)	⬆️

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[jasongrout]

Thanks!

[domoritz]

I'm going to merge this since the problems in the imports are just refactorings.

[jasongrout]

Do you have a timeline for release? (not to hurry or pressure you, just wanting to know when I can check back and resume work on jupyterlab/jupyterlab#7428).

[domoritz]

I'm hoping to get Vega-Lite 4 out in November so we don't block you. We can make a beta release anytime.