Add debugger safe point on assignment to global variables

runtime/observatory/tests/service/issue_27287_test.dart

Index: runtime/observatory/tests/service/issue_27287_test.dart
diff --git a/runtime/observatory/tests/service/issue_27287_test.dart b/runtime/observatory/tests/service/issue_27287_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..58633b3304ec09867b1e8997f9a7b3ec9a8c5603
--- /dev/null
+++ b/runtime/observatory/tests/service/issue_27287_test.dart
@@ -0,0 +1,33 @@
+// Copyright (c) 2016, 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 'package:observatory/service_io.dart';
+import 'service_test_common.dart';
+import 'dart:async';
+import 'test_helper.dart';
+import 'dart:developer';
+
+const int LINE_A = 19;
+const int LINE_B = 20;
+
+var libVariable;
+
+testMain() {
+  debugger();
+  print("Before");  // LINE_A
+  libVariable = 0;  // LINE_B
+  print("and after");
+}
+
+var tests = [
+  hasStoppedAtBreakpoint,
+  stoppedAtLine(LINE_A),
+  stepOver,
+  // Check that debugger stops at assignment to top-level variable.
+  stoppedAtLine(LINE_B),
+  resumeIsolate,
+];
+
+main(args) => runIsolateTests(args, tests, testeeConcurrent: testMain);