fix: decimal values in transformOrigin string parser

[MayankSharma-2812]

Summary:

Fixes incorrect parsing of decimal percentage and pixel values in the string form of transformOrigin.

The current tokenizer only matches integer numeric values followed by % or px. As a result, decimal pixel values are silently corrupted. For example:

processTransformOrigin('12.5px 7.5px');

currently returns:

[5, 5, 0]

instead of:

[12.5, 7.5, 0]

Decimal percentage values are also incorrectly tokenized. For example, 50.5% 30.2% is split into partial matches instead of preserving the decimal values.

This updates the numeric token pattern from \d+(?:%|px) to \d*\.?\d+(?:%|px), supporting decimal values such as 12.5px, 50.5%, and leading-dot decimal values such as .5%.

Regression coverage is added for decimal percentages, decimal pixels, and leading-dot decimal values.

Changelog:

[GENERAL] [FIXED] - Fix transformOrigin string parsing for decimal percentage and pixel values.

Test Plan:

Added regression coverage in processTransformOrigin-itest.js for:

• decimal percentages: 50.5% 30.2%
• decimal pixels: 12.5px 7.5px
• leading-dot decimals: .5% .5px

A focused local execution against processTransformOrigin confirmed:

Before fix:
"12.5px 7.5px" -> [5, 5, 0]

After fix:
"12.5px 7.5px" -> [12.5, 7.5, 0]

Also attempted the targeted Fantom integration test with:

node node_modules/jest/bin/jest.js --config private/react-native-fantom/config/jest.config.js packages/react-native/Libraries/StyleSheet/__tests__/processTransformOrigin-itest.js

The Fantom test could not complete locally because Metro failed to resolve a generated runtime setup path containing Windows path separators.

[meta-cla]

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[javache]

Can you validate that the native parser also correctly supports this? Please add unit tests to packages/react-native/ReactCommon/react/renderer/css/tests/CSSTransformOriginTest.cpp

[MayankSharma-2812]

Thanks for the review!

I checked the native parsing path and found that decimal numeric tokens are handled through CSSTokenizer::consumeNumber using fast_float::from_chars_advanced.

I’ve added equivalent coverage for decimal pixel (12.5px 7.5px) and percentage (50.5% 30.2%) values in CSSTransformOriginTest.cpp

[meta-codesync]

@javache has imported this pull request. If you are a Meta employee, you can view this in D111240577.

[MayankSharma-2812]

Thanks for the approval! I noticed the Facebook Internal - Linter check is failing, but the failure details are only available internally on Phabricator. Could you please let me know if there’s anything I need to update on my side? @javache