Hide the data table demo for now (#5060)

examples/flutter_gallery/lib/gallery/item.dart

@@ -90,12 +90,6 @@ final List<GalleryItem> kAllGalleryItems = <GalleryItem>[
     routeName: DatePickerDemo.routeName,
     buildRoute: (BuildContext context) => new DatePickerDemo()
   ),
-  new GalleryItem(
-    title: 'Data tables',
-    subtitle: 'Full-featured grid',
-    routeName: DataTableDemo.routeName,
-    buildRoute: (BuildContext context) => new DataTableDemo()
-  ),
   new GalleryItem(
     title: 'Dialog',
     subtitle: 'All kinds: simple, alert, fullscreen, etc',

examples/flutter_gallery/test_driver/transitions_perf_test.dart

@@ -31,7 +31,6 @@ final List<String> demoTitles = <String>[
   'Cards',
   'Chips',
   'Date picker',
-  'Data tables',
   'Dialog',
   'Expand/collapse list control',
   'Floating action button',