[heap] Reland "Add a guard for restarting the memory reducer after mark-compact."

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 14d3e610b1e1297a1f8e2a676d06933e8f0cd789..1fa424ca927ad79463e60a9caf535b2f4795e628 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -1013,6 +1013,7 @@ bool Heap::CollectGarbage(GarbageCollector collector,
           (committed_memory_before > committed_memory_after + MB) ||
           HasHighFragmentation(used_memory_after, committed_memory_after) ||
           (detached_contexts()->length() > 0);
+      event.committed_memory = committed_memory_after;
       if (deserialization_complete_) {
         memory_reducer_->NotifyMarkCompact(event);
       }