[turbofan] Small steps towards brokerization

Remove unnecessary call to Serialize.

Change a Handle cast to a Ref cast.

Add a CHECK to JSHeapBroker::SetFeedback that the source is valid.

Bug: v8:7790
Change-Id: I6a2f10d45456c6b128beff009016009457dc109c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1773248
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63421}

src/compiler/js-heap-broker.cc

@@ -4167,6 +4167,7 @@ NamedAccessFeedback::NamedAccessFeedback(NameRef const& name,
 
 void JSHeapBroker::SetFeedback(FeedbackSource const& source,
                                ProcessedFeedback const* feedback) {
+  CHECK(source.IsValid());
   auto insertion = feedback_.insert({source, feedback});
   CHECK(insertion.second);
 }

src/compiler/load-elimination.cc

@@ -985,9 +985,8 @@ Reduction LoadElimination::ReduceStoreField(Node* node,
     Type const new_value_type = NodeProperties::GetType(new_value);
     if (new_value_type.IsHeapConstant()) {
       // Record the new {object} map information.
-      AllowHandleDereference handle_dereference;
       ZoneHandleSet<Map> object_maps(
-          Handle<Map>::cast(new_value_type.AsHeapConstant()->Value()));
+          new_value_type.AsHeapConstant()->Ref().AsMap().object());
       state = state->SetMaps(object, object_maps, zone());
     }
   } else {

src/compiler/node-properties.cc

@@ -380,7 +380,10 @@ base::Optional<MapRef> NodeProperties::GetJSCreateMap(JSHeapBroker* broker,
     ObjectRef target = mtarget.Ref(broker);
     JSFunctionRef newtarget = mnewtarget.Ref(broker).AsJSFunction();
     if (newtarget.map().has_prototype_slot() && newtarget.has_initial_map()) {
-      if (broker->mode() == JSHeapBroker::kSerializing) newtarget.Serialize();
+      if (!newtarget.serialized()) {
+        TRACE_BROKER_MISSING(broker, "initial map on " << newtarget);
+        return base::nullopt;
+      }
       MapRef initial_map = newtarget.initial_map();
       if (initial_map.GetConstructor().equals(target)) {
         DCHECK(target.AsJSFunction().map().is_constructor());