fix build config to work the same when running on windows

[zxbodya]

While debugging failing windows build for #11578 (https://travis-ci.com/github/babel/babel/jobs/345463718) found a problem bundling babel-standalone: it was failing when trying to bundle ./lib/config/files/index.js instead of ./src/config/files/index-browser.ts from babel-core

Fixes for it are in two places:

• scripts/rollup-plugin-babel-source.js - load there was not handling windows path separator correctly
• babel.config.js - filter fix in rollup config, some modules failed to compile because babel config overrides were not applied on windows for the same path separator issue.

However, I still do not understand - how current master version can build correctly on windows… It looks like there is some other place in rollup to use browser field, but then - why it would change after converting sources to typescript

Q	A
Fixed Issues?
Patch: Bug Fix?
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

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[nicolo-ribaudo]

In Babel 8 I'd like to normalize the paths internally in @babel/core

[nicolo-ribaudo]

However, I still do not understand - how current master version can build correctly on windows… It looks like there is some other place in rollup to use browser field, but then - why it would change after converting sources to typescript

I admit that I have no idea 🤔

.

[nicolo-ribaudo]

https://github.com/zxbodya/babel/blob/997d00ed08f882156bdb0c5217b8f42b2e6babfa/packages/babel-core/package.json#L42

It seems that you didn't change it to .ts in your branch. Maybe it's what is causing the problem?

[zxbodya]

https://github.com/zxbodya/babel/blob/997d00ed08f882156bdb0c5217b8f42b2e6babfa/packages/babel-core/package.json#L42

It seems that you didn't change it to .ts in your branch. Maybe it's what is causing the problem?

Good catch, indeed changing it to .ts - made it work.

[zxbodya]

Good catch, indeed changing it to .ts - made it work.

It looks - load in scripts/rollup-plugin-babel-source.js can be removed completely… - I tried building on windows with fixes from PR and without them - both results in exactly the same babel-standalone file.

Also, apparently if not providing custom load - changes in babel.config.js are not really needed(probably somewhere in rollup paths are normalized for files it resolves).

@nicolo-ribaudo what you think? should I revert changes babel.config.js and instead of fixing - to remove load from scripts/rollup-plugin-babel-source.js to avoid confusion because of it?

[JLHwung]

However, I still do not understand - how current master version can build correctly on windows…

Currently our Travis Windows CI will skip standalone build, @babel/standalone is only built on Circle CI (Linux).

@zxbodya Can you rebase?

[zxbodya]

@JLHwung rebased it.
however: check my previous comment - might be this change it not really needed