Run dartfmt on all files under runtime.

runtime/observatory/tests/service/causal_async_stack_presence_test.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // VMOptions=--error_on_bad_type --error_on_bad_override  --verbose_debug
 
 import 'dart:developer';
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'service_test_common.dart';
 import 'test_helper.dart';
 
 const LINE_C = 18;
 const LINE_A = 23;
 const LINE_B = 29;
 
 foobar() {
   debugger();
-  print('foobar');  // LINE_C.
+  print('foobar'); // LINE_C.
 }
 
 helper() async {
   debugger();
-  print('helper');  // LINE_A.
+  print('helper'); // LINE_A.
   foobar();
 }
 
 testMain() {
   debugger();
-  helper();  // LINE_B.
+  helper(); // LINE_B.
 }
 
 var tests = [
   hasStoppedAtBreakpoint,
   stoppedAtLine(LINE_B),
   (Isolate isolate) async {
     ServiceMap stack = await isolate.getStack();
     // No causal frames because we are in a completely synchronous stack.
     expect(stack['asyncCausalFrames'], isNull);
   },
   resumeIsolate,
   hasStoppedAtBreakpoint,
   stoppedAtLine(LINE_A),
-
   (Isolate isolate) async {
     ServiceMap stack = await isolate.getStack();
     // Has causal frames (we are inside an async function)
     expect(stack['asyncCausalFrames'], isNotNull);
   },
-
   resumeIsolate,
   hasStoppedAtBreakpoint,
   stoppedAtLine(LINE_C),
-
   (Isolate isolate) async {
     ServiceMap stack = await isolate.getStack();
     // Has causal frames (we are inside a function called by an async function)
     expect(stack['asyncCausalFrames'], isNotNull);
   },
 ];
 
-main(args) => runIsolateTestsSynchronous(args,
-                                         tests,
-                                         testeeConcurrent: testMain);
+main(args) =>
+    runIsolateTestsSynchronous(args, tests, testeeConcurrent: testMain);