Avoid to list internal Arrays in _GetRetainingPath api

runtime/vm/service.cc

Index: runtime/vm/service.cc
diff --git a/runtime/vm/service.cc b/runtime/vm/service.cc
index c57890a6b0404b44a1e447cfeb2be8747eee10b6..a0f273418b01dce0c441e635b433cf9dabcb9b0d 100644
--- a/runtime/vm/service.cc
+++ b/runtime/vm/service.cc
@@ -2011,13 +2011,13 @@ static bool PrintRetainingPath(Thread* thread,
   for (intptr_t i = 0; i < limit; ++i) {
     JSONObject jselement(&elements);
     element = path.At(i * 2);
-    jselement.AddProperty("index", i);
     jselement.AddProperty("value", element);
     // Interpret the word offset from parent as list index or instance field.
     // TODO(koda): User-friendly interpretation for map entries.
     if (i > 0) {
       slot_offset ^= path.At((i * 2) - 1);
-      if (element.IsArray()) {
+      jselement.AddProperty("offset", slot_offset.Value());
+      if (element.IsArray() || element.IsGrowableObjectArray()) {
         intptr_t element_index = slot_offset.Value() -
             (Array::element_offset(0) >> kWordSizeLog2);
         jselement.AddProperty("parentListIndex", element_index);