The parseStyleInput function was incorrectly converting -webkit-text-stroke
to --text-stroke (a CSS variable) because:

1. The property is not in propertiesData (which only has longhand properties)
2. The existing logic converted any unknown property to a CSS variable

Fix: check shorthandProperties array before converting unknown properties
to CSS variables. -webkit-text-stroke is a known shorthand that should be
parsed normally, not treated as a user-defined custom property.

Add test to verify -webkit-text-stroke is parsed as a tuple value instead
of being converted to --text-stroke.

kof deleted the text-stroke branch

kof restored the text-stroke branch