Change from plural to singular (#5705)

Closes #5702

Update transitions_perf_test.dart

Update simple_smoke_test.dart

examples/flutter_gallery/lib/gallery/item.dart

@@ -59,7 +59,7 @@ final List<GalleryItem> kAllGalleryItems = <GalleryItem>[
     buildRoute: (BuildContext context) => new ShrineDemo()
   ),
   new GalleryItem(
-    title: 'Contacts',
+    title: 'Contact profile',
     category: 'Demos',
     subtitle: 'Highlights the flexible appbar',
     routeName: ContactsDemo.routeName,

examples/flutter_gallery/test/simple_smoke_test.dart

@@ -42,7 +42,7 @@ void main() {
     await tester.pump(const Duration(seconds: 1)); // end animation
 
     // Open Flexible space toolbar
-    await tester.tap(find.text('Contacts'));
+    await tester.tap(find.text('Contact profile'));
     await tester.pump(); // start animation
     await tester.pump(const Duration(seconds: 1)); // end animation
 

examples/flutter_gallery/test_driver/transitions_perf_test.dart

@@ -25,7 +25,7 @@ final List<String> demoTitles = <String>[
   // Demos
   // 'Pesto', TODO(hansmuller): restore when Pesto has a back button.
   'Shrine',
-  'Contacts',
+  'Contact profile',
   // Components
   'Buttons',
   'Cards',