[heap] Ensure quick progress of incremental marking near OOM.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index f29ba6b9687690e6a611658190299c1352ae614d..d8140166de893781d70fbb7c1ee09dca61c49b1c 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -1852,6 +1852,10 @@ class Heap {
     return (OldGenerationCapacity() + size) < MaxOldGenerationSize();
   }
 
+  bool IsCloseToOutOfMemory(size_t slack) {
+    return OldGenerationCapacity() + slack >= MaxOldGenerationSize();
+  }
+
   bool ShouldExpandOldGenerationOnAllocationFailure();
 
   enum class IncrementalMarkingLimit { kNoLimit, kSoftLimit, kHardLimit };