Track peak Zone memory usage and report it via HeapStatistics

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 6b75ea419814fbbbe2dd70bc0d300862e3bd2fde..ba260492a17e8ab140c92fd7486ff9064b8a93f1 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -5619,6 +5619,7 @@ HeapStatistics::HeapStatistics()
       used_heap_size_(0),
       heap_size_limit_(0),
       malloced_memory_(0),
+      peak_malloced_memory_(0),
       does_zap_garbage_(0) {}
 
 HeapSpaceStatistics::HeapSpaceStatistics(): space_name_(0),
@@ -7597,6 +7598,8 @@ void Isolate::GetHeapStatistics(HeapStatistics* heap_statistics) {
   heap_statistics->heap_size_limit_ = heap->MaxReserved();
   heap_statistics->malloced_memory_ =
       isolate->allocator()->GetCurrentMemoryUsage();
+  heap_statistics->peak_malloced_memory_ =
+      isolate->allocator()->GetMaxMemoryUsage();
   heap_statistics->does_zap_garbage_ = heap->ShouldZapGarbage();
 }