Make objects embedded in optimized code weak.

src/serialize.cc

Index: src/serialize.cc
diff --git a/src/serialize.cc b/src/serialize.cc
index b3a78780a9413da5d90e5403533bea82326da410..ef1461f1e9b6b5b634055cea1be441934495c90f 100644
--- a/src/serialize.cc
+++ b/src/serialize.cc
@@ -835,6 +835,8 @@ void Deserializer::Deserialize(Isolate* isolate) {
         isolate_->heap()->undefined_value());
   }
 
+  isolate_->heap()->InitializeWeakObjectToCodeTable();
+
   // Update data pointers to the external strings containing natives sources.
   for (int i = 0; i < Natives::GetBuiltinsCount(); i++) {
     Object* source = isolate_->heap()->natives_source_cache()->get(i);