Reland "Make sure that memory reducer makes progress in incremental marking""

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index d74d9cff958dfc1e316b425f4138e662de11f345..c66d62ac016e44a9ad2311f0bf67d9c1b9103859 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -1036,6 +1036,8 @@ class Heap {
   bool HasHighFragmentation();
   bool HasHighFragmentation(intptr_t used, intptr_t committed);
 
+  bool ShouldOptimizeForMemoryUsage() { return optimize_for_memory_usage_; }
+
   // ===========================================================================
   // Initialization. ===========================================================
   // ===========================================================================
@@ -1294,6 +1296,8 @@ class Heap {
       intptr_t step_size_in_bytes, double deadline_in_ms,
       IncrementalMarking::StepActions step_actions);
 
+  void FinalizeIncrementalMarkingIfComplete(const char* comment);
+
   IncrementalMarking* incremental_marking() { return &incremental_marking_; }
 
   // ===========================================================================