Run dartfmt on all files under runtime.

runtime/observatory/tests/service/causal_async_star_stack_contents_test.dart

Index: runtime/observatory/tests/service/causal_async_star_stack_contents_test.dart
diff --git a/runtime/observatory/tests/service/causal_async_star_stack_contents_test.dart b/runtime/observatory/tests/service/causal_async_star_stack_contents_test.dart
index 38b7e57f54c72e19cd7931e82641a5b50c74ef20..b859ca7795c0f03868131fd62199d9b9f239b4b2 100644
--- a/runtime/observatory/tests/service/causal_async_star_stack_contents_test.dart
+++ b/runtime/observatory/tests/service/causal_async_star_stack_contents_test.dart
@@ -16,14 +16,14 @@ const LINE_C = 21;
 
 foobar() async* {
   debugger();
-  yield 1;     // LINE_B.
+  yield 1; // LINE_B.
   debugger();
-  yield 2;     // LINE_C.
+  yield 2; // LINE_C.
 }
 
 helper() async {
   debugger();
-  print('helper');  // LINE_A.
+  print('helper'); // LINE_A.
   await for (var i in foobar()) {
     print('helper $i');
   }
@@ -48,7 +48,6 @@ var tests = [
   resumeIsolate,
   hasStoppedAtBreakpoint,
   stoppedAtLine(LINE_B),
-
   (Isolate isolate) async {
     ServiceMap stack = await isolate.getStack();
     // Has causal frames (we are inside an async function)
@@ -60,11 +59,9 @@ var tests = [
     expect(asyncStack[3].kind, equals(M.FrameKind.asyncSuspensionMarker));
     expect(asyncStack[4].toString(), contains('testMain'));
   },
-
   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)
@@ -88,6 +85,5 @@ var tests = [
   },
 ];
 
-main(args) => runIsolateTestsSynchronous(args,
-                                         tests,
-                                         testeeConcurrent: testMain);
+main(args) =>
+    runIsolateTestsSynchronous(args, tests, testeeConcurrent: testMain);