Sometimes the drawer doesn't fully close

sky/framework/animation/generator.dart

Index: sky/framework/animation/generator.dart
diff --git a/sky/framework/animation/generator.dart b/sky/framework/animation/generator.dart
index 0b5055050a98bcf8d1ddf73bfd5381dafe0cb2e7..98acf607f64594a347f3c75d2181c17d5c5429ba 100644
--- a/sky/framework/animation/generator.dart
+++ b/sky/framework/animation/generator.dart
@@ -73,7 +73,13 @@ class AnimationGenerator extends FrameGenerator {
       return math.min((timeStamp - startTime) / duration, 1.0);
     })
     .takeWhile(_checkForCompletion)
-    .map((t) =>  begin + (end - begin) * curve.transform(t));
+    .map(_transform);
+  }
+
+  double _transform(double t) {
+    if (_done)
+      return end;
+    return begin + (end - begin) * curve.transform(t);
   }
 
   bool _checkForCompletion(double t) {