Fix memory leak from snapshot printing

[rickhanlonii]

Summary

This PR fixes a memory leak introduced in #5020

Fixes #5234
Fixes #5239
Fixes #5157

Details

I initially confirmed that --detectLeaks is broken for all tests. The next step was to figure out if this was a bug in the way we detect leaks or if it's a legit leak. Using this repo, I walked the commits backward to find the last passing test.

That lead me to this commit. Nothing there is related to the leak detection, so I figured it must be a legit leak. From there I commented out lines until I could prove which line would fix the tests, then inspected the line.

It looks like we were keeping around references to the whole snapshot state. The fix is to remove the dependency using Array.from.

I'm not entirely sure how this is failing the environment leak detection, maybe the Snapshot State somehow keeps a reference to the environment?

Test plan

There are a couple of ways to test/demonstrate this.

1. via --detectLeaks

Considering this test repo, running yarn test from master will fail:

With this change they pass:

2. via React

This fix also fixes the memory issue @gaearon found in React for this command:

yarn test --coverage --runInBand --logHeapUsage

Result of Jest master (OOM at 1.5GB):

With this fix (capped at 500MB):

[codecov-io]

Codecov Report

Merging #5279 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #5279   +/-   ##
=======================================
  Coverage   60.98%   60.98%           
=======================================
  Files         203      203           
  Lines        6816     6816           
  Branches        3        4    +1     
=======================================
  Hits         4157     4157           
  Misses       2658     2658           
  Partials        1        1

Impacted Files	Coverage Δ
packages/jest-jasmine2/src/index.js	5.63% <0%> (ø)	⬆️

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[SimenB]

This is awesome. thank you so much!

[cpojer]

This is great work, thanks so much for diving in and triaging this. cc @mjesun the detectLeaks flag was helpful!!

[cpojer]

I just published 22.0.6 which includes this fix. cc @gaearon for React.

[rickhanlonii]

Yeah @mjesun the detectLeaks flag did all the work here

[kand]

@rickhanlonii thanks!

[mjesun]

@rickhanlonii thanks a lot for that! I'm really happy to see the --detectLeaks flag was useful! ☺️

You rock!

[github-actions]

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