Make sure we don't accidentially serialize type feedback

src/serialize.cc

Index: src/serialize.cc
diff --git a/src/serialize.cc b/src/serialize.cc
index 01c55a1226efedc5cca0d8bc1f80ad99dede6ba4..af8b3d012a384716b43d9dc77bfa9a6dd4d4b27c 100644
--- a/src/serialize.cc
+++ b/src/serialize.cc
@@ -2075,6 +2075,12 @@ ScriptData* CodeSerializer::Serialize(Isolate* isolate,
     PrintF("]\n");
   }
 
+  // The type feedback vector of this function must be clear.
+  if (info->feedback_vector()->IsCleared()) {
+    UNREACHABLE();
+    info->ClearTypeFeedbackInfo();
+  }
+
   // Serialize code object.
   SnapshotByteSink sink(info->code()->CodeSize() * 2);
   CodeSerializer cs(isolate, &sink, *source, info->code());