Debug garbage collector does not correctly remove cross-gen garbage

runtime/vm/object_test.cc

Index: runtime/vm/object_test.cc
diff --git a/runtime/vm/object_test.cc b/runtime/vm/object_test.cc
index 6e8de6bbc95b272e6a257b5bf659a5b052e0e86f..fe3dc26121e28f5159d5bd02cca5f5fda1dd7849 100644
--- a/runtime/vm/object_test.cc
+++ b/runtime/vm/object_test.cc
@@ -3364,7 +3364,8 @@ ISOLATE_UNIT_TEST_CASE(WeakProperty_PreserveCrossGen) {
     key ^= OneByteString::null();
     value ^= OneByteString::null();
   }
-  isolate->heap()->CollectAllGarbage();
+  isolate->heap()->CollectGarbage(Heap::kNew);
+  isolate->heap()->CollectGarbage(Heap::kOld);
   // Weak property key and value should survive due to cross-generation
   // pointers.
   EXPECT(weak.key() != Object::null());
@@ -3382,7 +3383,8 @@ ISOLATE_UNIT_TEST_CASE(WeakProperty_PreserveCrossGen) {
     key ^= OneByteString::null();
     value ^= OneByteString::null();
   }
-  isolate->heap()->CollectAllGarbage();
+  isolate->heap()->CollectGarbage(Heap::kNew);
+  isolate->heap()->CollectGarbage(Heap::kOld);
   // Weak property key and value should survive due to cross-generation
   // pointers.
   EXPECT(weak.key() != Object::null());