Cupertino navbar ellipsis fix (#118841)

* Passdown context

* make transitions ignore preffered text size

* Add test

* Add comment

* Return const constructor

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

@@ -1770,12 +1770,16 @@ class _NavigationBarTransition extends StatelessWidget {
     // The actual outer box is big enough to contain both the bottom and top
     // navigation bars. It's not a direct Rect lerp because some components
     // can actually be outside the linearly lerp'ed Rect in the middle of
-    // the animation, such as the topLargeTitle.
-    return SizedBox(
-      height: math.max(heightTween.begin!, heightTween.end!) + MediaQuery.paddingOf(context).top,
-      width: double.infinity,
-      child: Stack(
-        children: children,
+    // the animation, such as the topLargeTitle. The textScaleFactor is kept
+    // at 1 to avoid odd transitions between pages.
+    return MediaQuery(
+      data: MediaQuery.of(context).copyWith(textScaleFactor: 1),
+      child: SizedBox(
+        height: math.max(heightTween.begin!, heightTween.end!) + MediaQuery.paddingOf(context).top,
+        width: double.infinity,
+        child: Stack(
+          children: children,
+        ),
       ),
     );
   }

packages/flutter/test/cupertino/nav_bar_transition_test.dart

@@ -25,14 +25,18 @@ Future<void> startTransitionBetween(
   String? toTitle,
   TextDirection textDirection = TextDirection.ltr,
   CupertinoThemeData? theme,
+  double textScale = 1.0,
 }) async {
   await tester.pumpWidget(
     CupertinoApp(
       theme: theme,
       builder: (BuildContext context, Widget? navigator) {
-        return Directionality(
-          textDirection: textDirection,
-          child: navigator!,
+        return MediaQuery(
+          data: MediaQuery.of(context).copyWith(textScaleFactor: textScale),
+          child: Directionality(
+            textDirection: textDirection,
+            child: navigator!,
+          )
         );
       },
       home: const Placeholder(),
@@ -1225,6 +1229,14 @@ void main() {
     expect(find.text('Page 1'), findsOneWidget);
   });
 
+  testWidgets('textScaleFactor is set to 1.0 on transition', (WidgetTester tester) async {
+    await startTransitionBetween(tester, fromTitle: 'Page 1', textScale: 99);
+
+    await tester.pump(const Duration(milliseconds: 50));
+
+    expect(tester.firstWidget<RichText>(flying(tester, find.byType(RichText))).textScaleFactor, 1);
+  });
+
   testWidgets('Back swipe gesture cancels properly with transition', (WidgetTester tester) async {
     await startTransitionBetween(
       tester,