Fix default opacity assignments for unselected and selected icons in NavigationRail (#55902)

packages/flutter/lib/src/material/navigation_rail.dart

@@ -441,20 +441,20 @@ class _NavigationRailState extends State<NavigationRail> with TickerProviderStat
     final double minWidth = widget.minWidth ?? _minRailWidth;
     final double minExtendedWidth = widget.minExtendedWidth ?? _minExtendedRailWidth;
     final Color baseSelectedColor = theme.colorScheme.primary;
-    final Color baseColor = theme.colorScheme.onSurface.withOpacity(0.64);
+    final Color baseUnselectedColor = theme.colorScheme.onSurface.withOpacity(0.64);
     final IconThemeData defaultUnselectedIconTheme = widget.unselectedIconTheme ?? navigationRailTheme.unselectedIconTheme;
     final IconThemeData unselectedIconTheme = IconThemeData(
       size: defaultUnselectedIconTheme?.size ?? 24.0,
       color: defaultUnselectedIconTheme?.color ?? theme.colorScheme.onSurface,
-      opacity: defaultUnselectedIconTheme?.opacity ?? 1.0,
+      opacity: defaultUnselectedIconTheme?.opacity ?? 0.64,
     );
     final IconThemeData defaultSelectedIconTheme = widget.selectedIconTheme ?? navigationRailTheme.selectedIconTheme;
     final IconThemeData selectedIconTheme = IconThemeData(
       size: defaultSelectedIconTheme?.size ?? 24.0,
       color: defaultSelectedIconTheme?.color ?? theme.colorScheme.primary,
-      opacity: defaultSelectedIconTheme?.opacity ?? 0.64,
+      opacity: defaultSelectedIconTheme?.opacity ?? 1.0,
     );
-    final TextStyle unselectedLabelTextStyle = theme.textTheme.bodyText1.copyWith(color: baseColor).merge(widget.unselectedLabelTextStyle ?? navigationRailTheme.unselectedLabelTextStyle);
+    final TextStyle unselectedLabelTextStyle = theme.textTheme.bodyText1.copyWith(color: baseUnselectedColor).merge(widget.unselectedLabelTextStyle ?? navigationRailTheme.unselectedLabelTextStyle);
     final TextStyle selectedLabelTextStyle = theme.textTheme.bodyText1.copyWith(color: baseSelectedColor).merge(widget.selectedLabelTextStyle ?? navigationRailTheme.selectedLabelTextStyle);
     final double groupAlignment = widget.groupAlignment ?? navigationRailTheme.groupAlignment ?? -1.0;
     final NavigationRailLabelType labelType = widget.labelType ?? navigationRailTheme.labelType ?? NavigationRailLabelType.none;

packages/flutter/test/material/navigation_rail_theme_test.dart

@@ -29,10 +29,10 @@ void main() {
     expect(_railMaterial(tester).elevation, 0);
     expect(_selectedIconTheme(tester).size, 24.0);
     expect(_selectedIconTheme(tester).color, ThemeData().colorScheme.primary);
-    expect(_selectedIconTheme(tester).opacity, 0.64);
+    expect(_selectedIconTheme(tester).opacity, 1.0);
     expect(_unselectedIconTheme(tester).size, 24.0);
     expect(_unselectedIconTheme(tester).color, ThemeData().colorScheme.onSurface);
-    expect(_unselectedIconTheme(tester).opacity, 1.0);
+    expect(_unselectedIconTheme(tester).opacity, 0.64);
     expect(_selectedLabelStyle(tester).fontSize, 14.0);
     expect(_unselectedLabelStyle(tester).fontSize, 14.0);
     expect(_destinationsAlign(tester).alignment, Alignment.topCenter);