Babel-ignore node_modules on Windows consistently with others

[robhogan]

Summary:
CI failures in Windows JS tests recently (#41463) were caused by the triggering of Babel registration during tests, due to an import of packages/dev-middleware (index), breaking subsequent transformation of other tests.

Root cause

Example of a problematic import:

react-native/packages/dev-middleware/src/__tests__/ServerUtils.js

Line 15 in a5d8ea4

import {createDevMiddleware} from '../';

..which triggers a Babel registration:

react-native/packages/dev-middleware/src/index.js

Lines 16 to 18 in a5d8ea4

	if (!process.env.BUILD_EXCLUDE_BABEL_REGISTER) {
	require('../../../scripts/build/babel-register').registerForMonorepo();
	}

That registration behaves differently on Windows due to the ignore: [/\/node_modules\/\], which doesn't match against Windows path separators - Babel matches against system separators.

In particular, this changed whether node_modules/flow-parser was transformed when loading the RN Babel transformer. Transforming this file causes a console.warn from Babel due to its size:

[BABEL] Note: The code generator has deoptimised the styling of /Users/robhogan/workspace/react-native/node_modules/flow-parser/flow_parser.js as it exceeds the max of 500KB.

This throws due to our setup:

react-native/packages/react-native/jest/local-setup.js

Line 27 in a5d8ea4

throw new Error('console.warn() was called (see warning above)');

This all manifests as the first test following a Babel registration (within the same Jest worker) that requires the RN Babel transformer throwing during script transformation.

This change

This is the minimally disruptive change that makes Babel registration behaviour consistent between Windows and other platforms. The more durable solution here would be not to rely on any Babel registration for Jest, which has its own ScriptTransformer mechanism for running code from source. Given the fragile way our internal+OSS Babel set up hangs together that's a higher-risk change, so I'll follow up separately.

Changelog: [Internal]

Differential Revision: D53124578

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This pull request was exported from Phabricator. Differential Revision: D53124578

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D53124578

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This pull request has been merged in 41b256a.