Fix analyzer warning

examples/widgets/card_collection.dart

diff --git a/examples/widgets/card_collection.dart b/examples/widgets/card_collection.dart
index 305447b..b487f7c 100644
--- a/examples/widgets/card_collection.dart
+++ b/examples/widgets/card_collection.dart
@@ -392,12 +392,12 @@
 
   Shader _createShader(Rect bounds) {
     return new LinearGradient(
-        begin: bounds.topLeft,
-        end: bounds.bottomLeft,
+        begin: const Offset(0.0, 0.0),
+        end: const Offset(0.0, 1.0),
         colors: <Color>[const Color(0x00FFFFFF), const Color(0xFFFFFFFF)],
         stops: <double>[0.1, 0.35]
     )
-    .createShader();
+    .createShader(bounds);
   }
 
   Widget build(BuildContext context) {