samples/poppopwin: upgrade to first-class sample

samples/third_party/pop-pop-win/lib/src/canvas/title_element.dart

Index: samples/third_party/pop-pop-win/lib/src/canvas/title_element.dart
diff --git a/samples/third_party/pop-pop-win/lib/src/canvas/title_element.dart b/samples/third_party/pop-pop-win/lib/src/canvas/title_element.dart
deleted file mode 100644
index 1da705ba5dc60c439f363e846f437c449ee2c345..0000000000000000000000000000000000000000
--- a/samples/third_party/pop-pop-win/lib/src/canvas/title_element.dart
+++ /dev/null
@@ -1,20 +0,0 @@
-part of ppw_canvas;
-
-class GameTitleElement extends Thing {
-
-  GameTitleElement() : super(318, 96);
-
-  void drawOverride(CanvasRenderingContext2D ctx) {
-    _textureData.drawTextureKeyAt(ctx, 'logo_win.png');
-  }
-
-  GameElement get _gameElement => (parent as CanvasThing).parent;
-
-  TextureData get _textureData => _gameElement._textureData;
-
-  Game get _game => _gameElement._game;
-
-  void _mouseDirectlyOver(args) {
-    invalidateDraw();
-  }
-}