Use dartfmt on Observatory code

runtime/observatory/lib/src/models/objects/field.dart

Index: runtime/observatory/lib/src/models/objects/field.dart
diff --git a/runtime/observatory/lib/src/models/objects/field.dart b/runtime/observatory/lib/src/models/objects/field.dart
index 188f223cde3259ff224f52baf6deb8bdc941f249..8ac61ee8a08f260ba5424a822c4ed40e073253f4 100644
--- a/runtime/observatory/lib/src/models/objects/field.dart
+++ b/runtime/observatory/lib/src/models/objects/field.dart
@@ -28,11 +28,7 @@ abstract class FieldRef extends ObjectRef {
   bool get isStatic;
 }
 
-enum GuardClassKind {
-  unknown,
-  single,
-  dynamic
-}
+enum GuardClassKind { unknown, single, dynamic }
 
 abstract class Field extends Object implements FieldRef {
   /// [optional] The value of this field, if the field is static.