Fixed strong mode errors and warnings reachable from lib/observe.dart

lib/src/observable_box.dart

Index: lib/src/observable_box.dart
diff --git a/lib/src/observable_box.dart b/lib/src/observable_box.dart
index dfaf7ffb5960607615aa851acea920d9a125115c..af8df81e888a9363bad704f09308fec608b91854 100644
--- a/lib/src/observable_box.dart
+++ b/lib/src/observable_box.dart
@@ -20,7 +20,7 @@ class ObservableBox<T> extends ChangeNotifier {
   @reflectable T get value => _value;
 
   @reflectable void set value(T newValue) {
-    _value = notifyPropertyChange(#value, _value, newValue);
+    _value = notifyPropertyChange(#value, _value, newValue) as T;

[vsm, 2016/01/22 16:47:15]

Another cast from dynamic.

[Jennifer Messerly, 2016/01/22 17:45:00]

this one too could be either generic method for notifyPropertyChange, or:

notifyPropertyChange(#value, _value, newValue);
_value = newValue;


The return value from nPC is just a convenience. :)

[vsm, 2016/01/22 18:49:22]

Done.

   }
 
   String toString() => '#<$runtimeType value: $value>';