Add FLAG_trace_maps

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 35516320530849a2c14b2b72a7986d7b74912517..5d001f46908e736b47ccd4df0ac66a65ae30618e 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -1109,6 +1109,10 @@ class Isolate {
 
   std::string GetTurboCfgFileName();
 
+#if TRACE_MAPS
+  int GetNextUniqueSharedFunctionInfoId() { return next_unique_sfi_id_++; }
+#endif
+
  private:
   explicit Isolate(bool enable_serializer);
 
@@ -1311,6 +1315,10 @@ class Isolate {
 
   int next_optimization_id_;
 
+#if TRACE_MAPS
+  int next_unique_sfi_id_;
+#endif
+
   // List of callbacks when a Call completes.
   List<CallCompletedCallback> call_completed_callbacks_;