Make animation_demo a manual test (#6117)

This demo doesn't work properly in landscape and is confusing. It's
really more of a test of the material arc code.

Fixes #5710

dev/manual_tests/material_arc.dart

@@ -188,7 +188,7 @@ class _PointDemoState extends State<_PointDemo> {
     final MaterialPointArcTween arc = new MaterialPointArcTween(begin: _begin, end: _end);
     return new RawGestureDetector(
       behavior: _dragTarget == null ? HitTestBehavior.deferToChild : HitTestBehavior.opaque,
-      gestures: <Type, GestureRecognizerFactory>{ 
+      gestures: <Type, GestureRecognizerFactory>{
         ImmediateMultiDragGestureRecognizer: (ImmediateMultiDragGestureRecognizer recognizer) { // ignore: map_value_type_not_assignable, https://github.com/flutter/flutter/issues/5771
           return (recognizer ??= new ImmediateMultiDragGestureRecognizer())
             ..onStart = _handleOnStart;
@@ -407,8 +407,6 @@ class _ArcDemo {
 class AnimationDemo extends StatefulWidget {
   AnimationDemo({ Key key }) : super(key: key);
 
-  static const String routeName = '/animation';
-
   @override
   _AnimationDemoState createState() => new _AnimationDemoState();
 }
@@ -469,3 +467,9 @@ class _AnimationDemoState extends State<AnimationDemo> with TickerProviderStateM
     );
   }
 }
+
+void main() {
+  runApp(new MaterialApp(
+    home: new AnimationDemo()
+  ));
+}

examples/flutter_gallery/lib/demo/all.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-export 'animation_demo.dart';
 export 'bottom_navigation_demo.dart';
 export 'buttons_demo.dart';
 export 'contacts_demo.dart';

examples/flutter_gallery/lib/gallery/item.dart

@@ -229,13 +229,6 @@ final List<GalleryItem> kAllGalleryItems = <GalleryItem>[
     buildRoute: (BuildContext context) => new TooltipDemo()
   ),
   // Styles
-  new GalleryItem(
-    title: 'Animation',
-    subtitle: 'Material motion for points and rectangles',
-    category: 'Style',
-    routeName: AnimationDemo.routeName,
-    buildRoute: (BuildContext context) => new AnimationDemo()
-  ),
   new GalleryItem(
     title: 'Colors',
     subtitle: 'All of the predefined colors',

examples/flutter_gallery/test_driver/transitions_perf_test.dart

@@ -55,7 +55,6 @@ final List<String> demoTitles = <String>[
   'Time picker',
   'Tooltips',
   // Style
-  'Animation',
   'Colors',
   'Typography'
 ];