[heap] Add --stress-incremental-marking flag.

test/cctest/test-heap-profiler.cc

Index: test/cctest/test-heap-profiler.cc
diff --git a/test/cctest/test-heap-profiler.cc b/test/cctest/test-heap-profiler.cc
index b96e1615669ef1574aec21ce34d244d23aabc538..9605f70314c6882976811ca50877c1437d1f1c40 100644
--- a/test/cctest/test-heap-profiler.cc
+++ b/test/cctest/test-heap-profiler.cc
@@ -2030,12 +2030,15 @@ TEST(WeakGlobalHandle) {
 
   CHECK(!HasWeakGlobalHandle());
 
-  v8::Persistent<v8::Object> handle(env->GetIsolate(),
-                                    v8::Object::New(env->GetIsolate()));
+  v8::Persistent<v8::Object> handle;
+
+  handle.Reset(env->GetIsolate(), v8::Object::New(env->GetIsolate()));
   handle.SetWeak(&handle, PersistentHandleCallback,
                  v8::WeakCallbackType::kParameter);
 
   CHECK(HasWeakGlobalHandle());
+  CcTest::CollectAllGarbage();
+  EmptyMessageQueues(env->GetIsolate());
 }