Reapply "Remove @deprecated features."

pkg/observe/lib/src/observable.dart

Index: pkg/observe/lib/src/observable.dart
diff --git a/pkg/observe/lib/src/observable.dart b/pkg/observe/lib/src/observable.dart
index ee25819c96caa3aeda8c9cc1a4efbebd0d372912..f798f4446f46c541c25579890e93a1f8ea859a54 100644
--- a/pkg/observe/lib/src/observable.dart
+++ b/pkg/observe/lib/src/observable.dart
@@ -188,21 +188,6 @@ abstract class Observable {
   }
 }
 
-/**
- * *Deprecated* use [Observable.notifyPropertyChange] instead.
- *
- * This API should not be used as it creates a
- * [PropertyChangeRecord] without oldValue and newValue.
- *
- * Notify the property change. Shorthand for:
- *
- *     target.notifyChange(new PropertyChangeRecord(target, name, null, null));
- */
-@deprecated
-void notifyProperty(Observable target, Symbol name) {
-  target.notifyChange(new PropertyChangeRecord(target, name, null, null));
-}
-
 // TODO(jmesserly): remove the instance method and make this top-level method
 // public instead?
 // NOTE: this is not exported publically.