fix flow: resolve conditional style values in flattenStyle output

The conditional-value widening on style props leaked into flattenStyle's
return type, breaking ~15 consumers that expect concrete values (splitLayoutProps,
Image, Touchable, etc.). Widen flattenStyle's input bound to accept conditionals
and strip them from its output so a flattened style presents its resolved type.

Author: intergalacticspacehighway

packages/react-native/Libraries/StyleSheet/StyleSheetTypes.js

@@ -1106,8 +1106,13 @@ export type ____DangerouslyImpreciseStyleProp_Internal = StyleProp<
   >,
 >;
 
-export type ____DangerouslyImpreciseAnimatedStyleProp_Internal =
-  WithAnimatedValue<StyleProp<Partial<____DangerouslyImpreciseStyle_Internal>>>;
+export type ____DangerouslyImpreciseAnimatedStyleProp_Internal = WithAnimatedValue<
+  StyleProp<
+    ____WithConditionalValues_Internal<
+      Partial<____DangerouslyImpreciseStyle_Internal>,
+    >,
+  >,
+>;
 
 export type ____ViewStyleProp_Internal = StyleProp<
   ____WithConditionalValues_Internal<Readonly<Partial<____ViewStyle_Internal>>>,
@@ -1133,6 +1138,15 @@ type ____WithConditionalValues_Internal<out T> = {
   [K in keyof T]: T[K] | ____ConditionalStyleValue_Internal<T[K]>,
 };
 
+// Inverse of `____WithConditionalValues_Internal`: narrows each property back
+// to its base type. Conditional values are resolved natively, so a *flattened*
+// style presents its resolved (base) type to JS consumers.
+type ____ResolveConditionalValue_Internal<V> =
+  V extends ____ConditionalStyleValue_Internal<infer U> ? U : V;
+type ____ResolveConditionalValues_Internal<out T> = {
+  [K in keyof T]: ____ResolveConditionalValue_Internal<T[K]>,
+};
+
 export type ____Styles_Internal = {
   // $FlowFixMe[incompatible-exact]
   // $FlowFixMe[incompatible-type]
@@ -1164,4 +1178,6 @@ export type ____FlattenStyleProp_Internal<
 > =
   ____FlattenStyleProp_Helper<TStyleProp> extends empty // $FlowFixMe[unclear-type]
     ? any
-    : ____FlattenStyleProp_Helper<TStyleProp>;
+    : ____ResolveConditionalValues_Internal<
+        ____FlattenStyleProp_Helper<TStyleProp>,
+      >;