Parallel marking.

runtime/vm/heap_test.cc

Index: runtime/vm/heap_test.cc
diff --git a/runtime/vm/heap_test.cc b/runtime/vm/heap_test.cc
index 47cfafe2980823ee7141be0978929f50a3a33eb6..e609901f8c5e8a10a6f2f9d0a81c65a66318e6b2 100644
--- a/runtime/vm/heap_test.cc
+++ b/runtime/vm/heap_test.cc
@@ -12,6 +12,8 @@
 
 namespace dart {
 
+DECLARE_FLAG(int, marker_tasks);
+
 TEST_CASE(OldGC) {
   const char* kScriptChars =
   "main() {\n"
@@ -30,6 +32,25 @@ TEST_CASE(OldGC) {
 }
 
 
+TEST_CASE(OldGC_Unsync) {
+  FLAG_marker_tasks = 0;
+  const char* kScriptChars =
+  "main() {\n"
+  "  return [1, 2, 3];\n"
+  "}\n";
+  FLAG_verbose_gc = true;
+  Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, NULL);
+  Dart_Handle result = Dart_Invoke(lib, NewString("main"), 0, NULL);
+
+  EXPECT_VALID(result);
+  EXPECT(!Dart_IsNull(result));
+  EXPECT(Dart_IsList(result));
+  Isolate* isolate = Isolate::Current();
+  Heap* heap = isolate->heap();
+  heap->CollectGarbage(Heap::kOld);
+}
+
+
 TEST_CASE(LargeSweep) {
   const char* kScriptChars =
   "main() {\n"