Pass GC flags to incremental marker and start incremental marking with

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index df12e79beaaf030d3d1039d079f701d461c8dec4..0a050844d696fc84825ae432d3464b43d7337313 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -4650,8 +4650,8 @@ bool Heap::PerformIdleTimeAction(GCIdleTimeAction action,
       break;
     case DO_INCREMENTAL_MARKING: {
       if (incremental_marking()->IsStopped()) {
-        // TODO(ulan): take reduce_memory into account.
-        incremental_marking()->Start();
+        incremental_marking()->Start(
+            action.reduce_memory ? kReduceMemoryFootprintMask : kNoGCFlags);
       }
       double remaining_idle_time_in_ms = 0.0;
       do {