Add a version of heap snapshots that use only fields and stack frames as roots and only include ins…

runtime/observatory/tests/service/object_graph_stack_reference_test.dart

Index: runtime/observatory/tests/service/object_graph_stack_reference_test.dart
diff --git a/runtime/observatory/tests/service/object_graph_stack_reference_test.dart b/runtime/observatory/tests/service/object_graph_stack_reference_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9fc88ce4958832afc16bfa2cf03b5cacef48e0e6
--- /dev/null
+++ b/runtime/observatory/tests/service/object_graph_stack_reference_test.dart
@@ -0,0 +1,60 @@
+// 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
+
+import 'dart:developer';
+
+import 'test_helper.dart';
+import 'service_test_common.dart';
+
+import 'package:observatory/heap_snapshot.dart';
+import 'package:observatory/models.dart' as M;
+import 'package:observatory/object_graph.dart';
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+
+int arrayLength = 1024 * 1024;
+int minArraySize = arrayLength * 4;
+
+void script() {
+  var stackSlot = new List(arrayLength);
+  debugger();
+  print(stackSlot);  // Prevent optimizing away the stack slot.
+}
+
+checkForStackReferent(Isolate isolate) async {
+  Library corelib =
+      isolate.libraries.singleWhere((lib) => lib.uri == 'dart:core');
+  await corelib.load();
+  Class _List =
+      corelib.classes.singleWhere((cls) => cls.vmName.startsWith('_List'));
+  int kArrayCid = _List.vmCid;
+
+  RawHeapSnapshot raw =
+      await isolate.fetchHeapSnapshot(M.HeapSnapshotRoots.user, false).last;
+  HeapSnapshot snapshot = new HeapSnapshot();
+  await snapshot.loadProgress(isolate, raw).last;
+  ObjectGraph graph = snapshot.graph;
+
+  var root = graph.root;
+  var stack = graph.root.dominatorTreeChildren()
+      .singleWhere((child) => child.isStack);
+  expect(stack.retainedSize, greaterThanOrEqualTo(minArraySize));
+
+  bool foundBigArray = false;
+  for (var stackReferent in stack.dominatorTreeChildren()) {
+    if (stackReferent.vmCid == kArrayCid &&
+        stackReferent.shallowSize >= minArraySize) {
+      foundBigArray = true;
+    }
+  }
+}
+
+var tests = [
+  hasStoppedAtBreakpoint,
+  checkForStackReferent,
+  resumeIsolate,
+];
+
+main(args) => runIsolateTests(args, tests, testeeConcurrent: script);