Small fidelity adjustments for Cupertino (#18104)

bin/internal/goldens.version

-17b9d558228edad27729a0c1823430d73cb26608
+760320e3fc8ccd12deb4066bd4033a98d078359f

packages/flutter/lib/src/cupertino/icons.dart

@@ -86,6 +86,9 @@ class CupertinoIcons {
   /// A thicker left chevron used in iOS for the navigation bar back button.
   static const IconData back = const IconData(0xf3cf, fontFamily: iconFont, fontPackage: iconFontPackage, matchTextDirection: true);
 
+  /// A thicker right chevron that's the reverse of [back].
+  static const IconData forward = const IconData(0xf3d1, fontFamily: iconFont, fontPackage: iconFontPackage, matchTextDirection: true);
+
   /// Outline of a simple front-facing house.
   static const IconData home = const IconData(0xf447, fontFamily: iconFont, fontPackage: iconFontPackage);
 

packages/flutter/lib/src/cupertino/nav_bar.dart

@@ -18,7 +18,7 @@ const double _kNavBarPersistentHeight = 44.0;
 
 /// Size increase from expanding the navigation bar into an iOS-11-style large title
 /// form in a [CustomScrollView].
-const double _kNavBarLargeTitleHeightExtension = 56.0;
+const double _kNavBarLargeTitleHeightExtension = 52.0;
 
 /// Number of logical pixels scrolled down before the title text is transferred
 /// from the normal navigation bar to a big title below the navigation bar.
@@ -46,10 +46,10 @@ const Border _kDefaultNavBarBorder = const Border(
 );
 
 const TextStyle _kLargeTitleTextStyle = const TextStyle(
-  fontFamily: '.SF UI Text',
+  fontFamily: '.SF Pro Display',
   fontSize: 34.0,
   fontWeight: FontWeight.w700,
-  letterSpacing: -0.26,
+  letterSpacing: 0.24,
   color: CupertinoColors.black,
 );
 

packages/flutter/test/cupertino/nav_bar_test.dart

@@ -171,7 +171,7 @@ void main() {
     expect(tester.getTopRight(find.byKey(trailingKey)), const Offset(800.0 - 16.0 - 40.0, 10.0));
 
     // Top and left padding is applied to large title.
-    expect(tester.getTopLeft(find.byKey(titleKey)), const Offset(16.0 + 20.0, 58.0 + 10.0));
+    expect(tester.getTopLeft(find.byKey(titleKey)), const Offset(16.0 + 20.0, 54.0 + 10.0));
   });
 
   testWidgets('Large title nav bar scrolls', (WidgetTester tester) async {
@@ -229,7 +229,7 @@ void main() {
     ]);
 
     expect(tester.getTopLeft(find.widgetWithText(OverflowBox, 'Title')).dy, 44.0);
-    expect(tester.getSize(find.widgetWithText(OverflowBox, 'Title')).height, 56.0);
+    expect(tester.getSize(find.widgetWithText(OverflowBox, 'Title')).height, 52.0);
 
     scrollController.jumpTo(600.0);
     await tester.pump(); // Once to trigger the opacity animation.
@@ -313,7 +313,7 @@ void main() {
       isNull,
     );
 
-    expect(tester.getBottomLeft(find.text('Title')).dy, 44.0 + 56.0 - 8.0); // Static part + extension - padding.
+    expect(tester.getBottomLeft(find.text('Title')).dy, 44.0 + 52.0 - 8.0); // Static part + extension - padding.
 
     scrollController.jumpTo(600.0);
     await tester.pump(); // Once to trigger the opacity animation.