[heap] Thread through GC flags in memory reducer and incremental marking.

test/cctest/test-heap.cc

Index: test/cctest/test-heap.cc
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index 48ec24b3581d090bf1b8c1ea4042c1393679ee0a..8703871daf3631b4027914c3505cb737895c0e25 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -2812,7 +2812,8 @@ HEAP_TEST(GCFlags) {
   marking->Start(Heap::kReduceMemoryFootprintMask);
   CHECK_NE(0, heap->current_gc_flags() & Heap::kReduceMemoryFootprintMask);
 
-  heap->Scavenge();
+  heap->CollectGarbage(NEW_SPACE);
+  // NewSpace scavenges should not overwrite the flags.
   CHECK_NE(0, heap->current_gc_flags() & Heap::kReduceMemoryFootprintMask);
 
   heap->CollectAllGarbage(Heap::kAbortIncrementalMarkingMask);