[runtime] Replace global object link with native context link in all contexts.

src/snapshot/serialize.cc

Index: src/snapshot/serialize.cc
diff --git a/src/snapshot/serialize.cc b/src/snapshot/serialize.cc
index 4affefe7729065426b4f55fc6ecdd396be14d3bd..183f7554835b334f6cd1b1e05c5249a75fe17d9a 100644
--- a/src/snapshot/serialize.cc
+++ b/src/snapshot/serialize.cc
@@ -1853,6 +1853,8 @@ void PartialSerializer::SerializeObject(HeapObject* obj, HowToCode how_to_code,
   ObjectSerializer serializer(this, obj, sink_, how_to_code, where_to_point);
   serializer.Serialize();
 
+  // TODO(yangguo): We probably only need ScriptContext here for post-
+  // processing in Genesis::HookUpGlobalThisBinding.
   if (obj->IsContext() &&
       Context::cast(obj)->global_object() == global_object_) {
     // Context refers to the current global object. This reference will