Reset removed shadow, editable and persistentScrollbar props to their defaults

[YevheniiKotyrlo]

Summary:

A prop removed from a component reaches the C++ props as null, and convertRawProp then returns its fallback argument. For these props the fallback differs from the field's declared default, so a component that had the prop and lost it is left with a value that a component which never had it does not have:

Prop	Declared default	After removal
shadowRadius	3	0
shadowOffset	{width: 0, height: -3}	{width: 0, height: 0}
editable (TextInput)	true	false
persistentScrollbar (ScrollView)	false	true
sendMomentumEvents, nestedScrollEnabled (Android ScrollView)	false	true

On iOS, RCTViewComponentView applies the shadow values to the layer, so a view that sets shadowRadius or shadowOffset conditionally (a raised card, a pressed state) gets layer.shadowRadius = 0 and layer.shadowOffset = {0, 0} once they are removed, instead of the defaults it started with. On Android, the props diff of enablePropsUpdateReconciliationAndroid reads the same values, so a TextInput that drops editable={false} stays read-only and a ScrollView that drops persistentScrollbar keeps it. ScrollView always passes sendMomentumEvents and nestedScrollEnabled, so those two only reach a direct user of the native component.

Each fallback is now the declared default, the value setProp (enableCppPropsIteratorSetter) already resets these props to.

Changelog:

[GENERAL] [FIXED] - Reset a removed shadowRadius, shadowOffset, editable or persistentScrollbar prop to its default

Test Plan:

• ViewPropsTest and BaseTextInputPropsTest parse a prop, then its removal, and compare the result with a default-constructed props object. On main they fail with removed.shadowRadius 0 against 3, removed.shadowOffset.height 0 against -3, and removed.editable false against true. BaseTextInputProps had no tests, so textinput/tests/ is new: the SwiftPM target excludes it as the other targets exclude theirs, and it needs a test target in the internal build.
• A Fantom case in ScrollView-itest.js renders persistentScrollbar={true} and then no prop; on main the second render still carries persistentScrollbar="true".
• I ran these in the reactnativecommunity/react-native-android image, linking the gtests against the Fantom runner's ReactCommon build: the new tests fail on main and pass with this change, and the whole Fantom suite passes with it. clang-format 21.1.2, Prettier, ESLint and Flow pass.
• RNTester release builds of main and of this change on an iPad (iOS 27.0.1): a view that loses shadowRadius and shadowOffset draws no shadow on main and the default one with this change (before and after).

[YevheniiKotyrlo]

Device evidence — before / after

UNFIXED — the right card loses its shadow once shadowRadius and shadowOffset are removed: its layer is left at radius 0 and offset {0, 0}, so the shadow sits behind the card.

FIXED — the right card draws the default shadow, like the left card, which never had either prop.

before — main at 68b7ce2abe	after — with this PR

iPad Pro 12.9-inch (4th generation), iOS 27.0.1: RNTester release builds of main at 68b7ce2abe and of this PR at 4968cd54b7, one session, with the scene below as the root component and a label naming the build. Both cards keep shadowColor and shadowOpacity; the right one renders with shadowRadius: 12 and shadowOffset: {width: 0, height: 12}, and an effect removes both after the first commit. The two frames differ only in the right card's shadow and the label: the 8 px band above that card's top edge averages a luminance of 226.7 on main, the background's, and 105.8 with this change, the left card's.

Scene

const SHADOW = {shadowColor: '#000000', shadowOpacity: 0.9};
const SHADOW_GEOMETRY = {shadowRadius: 12, shadowOffset: {width: 0, height: 12}};

function ShadowRemovalExample() {
  const [removed, setRemoved] = React.useState(false);
  React.useEffect(() => {
    setRemoved(true);
  }, []);
  return (
    <View style={styles.row}>
      <View style={[styles.card, SHADOW]} />
      <View style={[styles.card, SHADOW, removed ? null : SHADOW_GEOMETRY]} />
    </View>
  );
}

const styles = StyleSheet.create({
  row: {flexDirection: 'row', gap: 72},
  card: {width: 200, height: 140, borderRadius: 16, backgroundColor: '#ffffff'},
});

[YevheniiKotyrlo]

The red iOS jobs come from one download: test_ios_rntester (Release, false) lost its connection fetching the Hermes release tarball (curl: (56) Recv failure: Connection reset by peer), and the test_e2e_ios_rntester Release jobs then find no RNTesterApp-NewArch-Release artifact.

[meta-codesync]

@javache has imported this pull request. If you are a Meta employee, you can view this in D125706127.