src: make edge names in BaseObjects more descriptive in heap snapshots

Previously these were named "wrapper" and "wrapped", which can be
somewhat difficult to understand. This patch renames them to
"javascript_to_native" and "native_to_javascript".

Author: joyeecheung

src/memory_tracker-inl.h

@@ -318,8 +318,8 @@ MemoryRetainerNode* MemoryTracker::AddNode(const MemoryRetainer* retainer,
   if (CurrentNode() != nullptr) graph_->AddEdge(CurrentNode(), n, edge_name);
 
   if (n->JSWrapperNode() != nullptr) {
-    graph_->AddEdge(n, n->JSWrapperNode(), "wrapped");
-    graph_->AddEdge(n->JSWrapperNode(), n, "wrapper");
+    graph_->AddEdge(n, n->JSWrapperNode(), "native_to_javascript");
+    graph_->AddEdge(n->JSWrapperNode(), n, "javascript_to_native");
   }
 
   return n;