Run dartfmt on all files under runtime.

runtime/observatory/tests/observatory_ui/mocks/repositories/reachable_size.dart

Index: runtime/observatory/tests/observatory_ui/mocks/repositories/reachable_size.dart
diff --git a/runtime/observatory/tests/observatory_ui/mocks/repositories/reachable_size.dart b/runtime/observatory/tests/observatory_ui/mocks/repositories/reachable_size.dart
index db931000ab0d70b24e0e595145a3768a770582f0..786e71993ca5704b275a5898fab1cd2a253045df 100644
--- a/runtime/observatory/tests/observatory_ui/mocks/repositories/reachable_size.dart
+++ b/runtime/observatory/tests/observatory_ui/mocks/repositories/reachable_size.dart
@@ -4,8 +4,8 @@
 
 part of mocks;
 
-typedef Future<M.Guarded<M.Instance>>
-        ReachableSizeRepositoryMockGetter(M.IsolateRef i, String id);
+typedef Future<M.Guarded<M.Instance>> ReachableSizeRepositoryMockGetter(
+    M.IsolateRef i, String id);
 
 class ReachableSizeRepositoryMock implements M.ReachableSizeRepository {
   final ReachableSizeRepositoryMockGetter _getter;
@@ -15,10 +15,9 @@ class ReachableSizeRepositoryMock implements M.ReachableSizeRepository {
       return _getter(i, id);
     }
     return new Future.value(
-      new GuardedMock<M.Instance>.fromSentinel(new SentinelMock())
-    );
+        new GuardedMock<M.Instance>.fromSentinel(new SentinelMock()));
   }
 
   ReachableSizeRepositoryMock({ReachableSizeRepositoryMockGetter getter})
-    : _getter = getter;
+      : _getter = getter;
 }