Use dartfmt on Observatory code

runtime/observatory/lib/src/repositories/strongly_reachable_instances.dart

Index: runtime/observatory/lib/src/repositories/strongly_reachable_instances.dart
diff --git a/runtime/observatory/lib/src/repositories/strongly_reachable_instances.dart b/runtime/observatory/lib/src/repositories/strongly_reachable_instances.dart
index bcfff96e1eacaee1be8f3d58721c19a6b7bc2c73..a015928458a60f64eaa8ee690b80b82df1e6d34c 100644
--- a/runtime/observatory/lib/src/repositories/strongly_reachable_instances.dart
+++ b/runtime/observatory/lib/src/repositories/strongly_reachable_instances.dart
@@ -7,13 +7,12 @@ part of repositories;
 class StronglyReachableInstancesRepository
     implements M.StronglyReachableInstancesRepository {
   Future<M.InstanceSet> get(M.IsolateRef i, M.ClassRef c,
-                                           {int limit: 100}) async {
+      {int limit: 100}) async {
     S.Isolate isolate = i as S.Isolate;
     S.Class cls = c as S.Class;
     assert(isolate != null);
     assert(cls != null);
     assert(limit != null);
-    return (await isolate.getInstances(cls, limit))
-        as S.InstanceSet;
+    return (await isolate.getInstances(cls, limit)) as S.InstanceSet;
   }
 }