Added zone tracing

src/zone/zone.h

Index: src/zone/zone.h
diff --git a/src/zone/zone.h b/src/zone/zone.h
index f97662ab20ab9e7aad2f4c98588d3ab43ff8f720..00a254a661530bacf79014f6e566fc8404ab8740 100644
--- a/src/zone/zone.h
+++ b/src/zone/zone.h
@@ -31,7 +31,7 @@ namespace internal {
 // from multi-threaded code.
 class V8_EXPORT_PRIVATE Zone final {
  public:
-  explicit Zone(AccountingAllocator* allocator);
+  explicit Zone(AccountingAllocator* allocator, const char* name = "unnamed");
   ~Zone();
 
   // Allocate 'size' bytes of memory in the Zone; expands the Zone by
@@ -50,6 +50,8 @@ class V8_EXPORT_PRIVATE Zone final {
     return segment_bytes_allocated_ > kExcessLimit;
   }
 
+  const char* name() const { return name_; }
+
   size_t allocation_size() const { return allocation_size_; }
 
   AccountingAllocator* allocator() const { return allocator_; }
@@ -104,6 +106,7 @@ class V8_EXPORT_PRIVATE Zone final {
   AccountingAllocator* allocator_;
 
   Segment* segment_head_;
+  const char* name_;
 };
 
 // ZoneObject is an abstraction that helps define classes of objects