Revert of [turbofan] Properly handle dictionary maps in the prototype chain.

src/compiler/js-native-context-specialization.cc

Index: src/compiler/js-native-context-specialization.cc
diff --git a/src/compiler/js-native-context-specialization.cc b/src/compiler/js-native-context-specialization.cc
index ed351e14044f6e357a52d1037f795c452814bec4..50c0851612cbcf1d01e9802ee0db0b43788b4875 100644
--- a/src/compiler/js-native-context-specialization.cc
+++ b/src/compiler/js-native-context-specialization.cc
@@ -225,8 +225,7 @@
     // Determine actual holder and perform prototype chain checks.
     Handle<JSObject> holder;
     if (access_info.holder().ToHandle(&holder)) {
-      this_effect = CheckPrototypeMaps(receiver_type, native_context, holder,
-                                       this_effect, this_control);
+      AssumePrototypesStable(receiver_type, native_context, holder);
     }
 
     // Generate the actual property access.
@@ -669,8 +668,7 @@
     // not compatible with (monomorphic) keyed stores.
     Handle<JSObject> holder;
     if (access_info.holder().ToHandle(&holder)) {
-      this_effect = CheckPrototypeMaps(receiver_type, native_context, holder,
-                                       this_effect, this_control);
+      AssumePrototypesStable(receiver_type, native_context, holder);
     }
 
     // TODO(bmeurer): We currently specialize based on elements kind. We should
@@ -755,9 +753,8 @@
         if (receiver_type->NowIs(initial_holey_array_type) &&
             isolate()->IsFastArrayConstructorPrototypeChainIntact()) {
           // Add a code dependency on the array protector cell.
-          this_effect = CheckPrototypeMaps(
-              receiver_type, native_context,
-              isolate()->initial_object_prototype(), this_effect, this_control);
+          AssumePrototypesStable(receiver_type, native_context,
+                                 isolate()->initial_object_prototype());
           dependencies()->AssumePropertyCell(factory()->array_protector());
           // Turn the hole into undefined.
           mode = CheckTaggedHoleMode::kConvertHoleToUndefined;
@@ -775,9 +772,8 @@
         if (receiver_type->NowIs(initial_holey_array_type) &&
             isolate()->IsFastArrayConstructorPrototypeChainIntact()) {
           // Add a code dependency on the array protector cell.
-          this_effect = CheckPrototypeMaps(
-              receiver_type, native_context,
-              isolate()->initial_object_prototype(), this_effect, this_control);
+          AssumePrototypesStable(receiver_type, native_context,
+                                 isolate()->initial_object_prototype());
           dependencies()->AssumePropertyCell(factory()->array_protector());
           // Return the signaling NaN hole directly if all uses are truncating.
           mode = CheckFloat64HoleMode::kAllowReturnHole;
@@ -960,9 +956,10 @@
                            p.language_mode(), store_mode);
 }
 
-Node* JSNativeContextSpecialization::CheckPrototypeMaps(
+
+void JSNativeContextSpecialization::AssumePrototypesStable(
     Type* receiver_type, Handle<Context> native_context,
-    Handle<JSObject> holder, Node* effect, Node* control) {
+    Handle<JSObject> holder) {
   // Determine actual holder and perform prototype chain checks.
   for (auto i = receiver_type->Classes(); !i.Done(); i.Advance()) {
     Handle<Map> map = i.Current();
@@ -973,28 +970,8 @@
             .ToHandle(&constructor)) {
       map = handle(constructor->initial_map(), isolate());
     }
-    for (PrototypeIterator j(map); !j.IsAtEnd(); j.Advance()) {
-      Handle<JSReceiver> const current =
-          PrototypeIterator::GetCurrent<JSReceiver>(j);
-      Handle<Map> current_map(current->map(), isolate());
-      if (current_map->is_stable()) {
-        dependencies()->AssumeMapStable(current_map);
-      } else {
-        // TODO(bmeurer): Introduce a dedicated CheckMaps operator.
-        Node* prototype = jsgraph()->HeapConstant(current);
-        Node* prototype_map = effect =
-            graph()->NewNode(simplified()->LoadField(AccessBuilder::ForMap()),
-                             prototype, effect, control);
-        Node* check = graph()->NewNode(
-            simplified()->ReferenceEqual(Type::Internal()), prototype_map,
-            jsgraph()->HeapConstant(current_map));
-        effect =
-            graph()->NewNode(simplified()->CheckIf(), check, effect, control);
-      }
-      if (holder.is_identical_to(current)) break;
-    }
-  }
-  return effect;
+    dependencies()->AssumePrototypeMapsStable(map, holder);
+  }
 }
 
 bool JSNativeContextSpecialization::ExtractReceiverMaps(