Removed all analyzer issues from tests

runtime/observatory/tests/service/get_isolate_after_stack_overflow_error_test.dart

Index: runtime/observatory/tests/service/get_isolate_after_stack_overflow_error_test.dart
diff --git a/runtime/observatory/tests/service/get_isolate_after_async_error_test.dart b/runtime/observatory/tests/service/get_isolate_after_stack_overflow_error_test.dart
similarity index 58%
copy from runtime/observatory/tests/service/get_isolate_after_async_error_test.dart
copy to runtime/observatory/tests/service/get_isolate_after_stack_overflow_error_test.dart
index a0c531d16e0c5114dc22cb86424b2fe75116ed06..0223218d210765602f7245cef3f60584ca5a2694 100644
--- a/runtime/observatory/tests/service/get_isolate_after_async_error_test.dart
+++ b/runtime/observatory/tests/service/get_isolate_after_stack_overflow_error_test.dart
@@ -8,8 +8,13 @@ import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'service_test_common.dart';
 
-doThrow() async {
-  throw "oh no"; // Line 13.
+// Non tailable recursive function that should trigger a Stack Overflow.
+num factorialGrowth([num n = 1]) {
+  return factorialGrowth(n + 1) * n;
+}
+
+void nonTailableRecursion() {
+  factorialGrowth();
 }
 
 var tests = [
@@ -18,11 +23,11 @@ var tests = [
   (Isolate isolate) async {
     await isolate.reload();
     expect(isolate.error, isNotNull);
-    expect(isolate.error.message.contains('oh no'), isTrue);
+    expect(isolate.error.message.contains('Stack Overflow'), isTrue);
   }
 ];
 
 main(args) async => runIsolateTests(args,
-                                    tests,
-                                    pause_on_exit: true,
-                                    testeeConcurrent: doThrow);
+                              tests,
+                              pause_on_exit: true,
+                              testeeConcurrent: nonTailableRecursion);