fix: parse Image srcSet densities consistently

[ya-nsh]

Summary

• parse Image srcSet entries even when there is no space after the comma
• keep fractional density descriptors like 1.5x
• keep bare x descriptors out of the source list

Changelog:

[General] [Fixed] - Parse Image srcSet density descriptors consistently

Test Plan

• yarn jest packages/react-native/Libraries/Image/__tests__/ImageSourceUtils-test.js --runInBand
• npx prettier --check packages/react-native/Libraries/Image/ImageSourceUtils.js packages/react-native/Libraries/Image/__tests__/ImageSourceUtils-test.js
• yarn flow-check

[meta-codesync]

@javache has imported this pull request. If you are a Meta employee, you can view this in D105689719.

[javache]

Number('') returns 0 (not NaN), so a bare 'x' descriptor (no preceding number) now silently produces scale: 0 instead of being filtered by the isNaN check.

Maybe use parseFloat() instead of Number()? parseFloat('') returns NaN (matching the old guard behavior) while parseFloat('1.5') still correctly returns 1.5.

[ya-nsh]

Good catch, thanks. I switched this to parseFloat and added a regression case for the bare x descriptor so it stays filtered out.

I also fixed the changelog heading in the PR body.

Validated with:

• yarn jest packages/react-native/Libraries/Image/__tests__/ImageSourceUtils-test.js --runInBand
• npx prettier --check packages/react-native/Libraries/Image/ImageSourceUtils.js packages/react-native/Libraries/Image/__tests__/ImageSourceUtils-test.js
• yarn flow-check

Updated commit: 5c47a49

[meta-codesync]

@javache merged this pull request in e4cf0a1.

[react-native-bot]

This pull request was successfully merged by @ya-nsh in e4cf0a1

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