Make object-observe test case resilient against GC stress.

test/cctest/test-object-observe.cc

Index: test/cctest/test-object-observe.cc
diff --git a/test/cctest/test-object-observe.cc b/test/cctest/test-object-observe.cc
index 558b0d1a30050be4446e388ca5c6d4e801a6db10..190bbb29ca18636033557264cc72b2705a56d270 100644
--- a/test/cctest/test-object-observe.cc
+++ b/test/cctest/test-object-observe.cc
@@ -427,7 +427,7 @@ TEST(ObservationWeakMap) {
   CHECK_EQ(1, NumberOfElements(observerInfoMap));
   CHECK_EQ(1, NumberOfElements(objectInfoMap));
   CHECK_EQ(1, NumberOfElements(notifierTargetMap));
-  HEAP->CollectAllGarbage(i::Heap::kNoGCFlags);
+  HEAP->CollectAllGarbage(i::Heap::kAbortIncrementalMarkingMask);
   CHECK_EQ(0, NumberOfElements(observerInfoMap));
   CHECK_EQ(0, NumberOfElements(objectInfoMap));
   CHECK_EQ(0, NumberOfElements(notifierTargetMap));