[observe] use consistent comment style

pkg/observe/lib/src/change_record.dart

Index: pkg/observe/lib/src/change_record.dart
diff --git a/pkg/observe/lib/src/change_record.dart b/pkg/observe/lib/src/change_record.dart
index 985e3721217b132c7c96e9b143fc0546193f1d3f..576a1737a1ae80ad1fc8b10f6669efe2b983b11f 100644
--- a/pkg/observe/lib/src/change_record.dart
+++ b/pkg/observe/lib/src/change_record.dart
@@ -7,22 +7,22 @@ library observe.src.change_record;
 import 'package:observe/observe.dart';
 
 
-/** Records a change to an [Observable]. */
+/// Records a change to an [Observable].
 // TODO(jmesserly): remove this type
 abstract class ChangeRecord {}
 
-/** A change record to a field of an observable object. */
+/// A change record to a field of an observable object.
 class PropertyChangeRecord<T> extends ChangeRecord {
-  /** The object that changed. */
+  /// The object that changed.
   final object;
 
-  /** The name of the property that changed. */
+  /// The name of the property that changed.
   final Symbol name;
 
-  /** The previous value of the property. */
+  /// The previous value of the property.
   final T oldValue;
 
-  /** The new value of the property. */
+  /// The new value of the property.
   final T newValue;
 
   PropertyChangeRecord(this.object, this.name, this.oldValue, this.newValue);