Revert of [stubs] KeyedLoadIC_Generic: prototype chain lookup support...

Revert of [stubs] KeyedLoadIC_Generic: prototype chain lookup support (patchset #2 id:20001 of https://codereview.chromium.org/2652213003/ )

Reason for revert:
Speculative revert for breaking a layout test:
https://build.chromium.org/p/client.v8.fyi/builders/V8-Blink%20Linux%2064/builds/13113

Unfortunately, the test results archive is not giving much info this time.

Original issue's description:
> [stubs] KeyedLoadIC_Generic: prototype chain lookup support
>
> Performing lookups on the prototype chain in the stub avoids a
> bunch of slow-path runtime calls. For now, only receivers with
> dictionary-mode properties do this; fast-mode receivers will follow
> if it's beneficial.
>
> Review-Url: https://codereview.chromium.org/2652213003
> Cr-Commit-Position: refs/heads/master@{#42751}
> Committed: https://chromium.googlesource.com/v8/v8/+/82e10f5fbacbbd71bc65e99322f432470692bf41

TBR=ishell@chromium.org,jkummerow@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2657393002
Cr-Commit-Position: refs/heads/master@{#42754}

src/ic/accessor-assembler.cc

@@ -1403,8 +1403,7 @@ void AccessorAssembler::KeyedLoadICGeneric(const LoadICParameters* p) {
   Variable var_value(this, MachineRepresentation::kTagged);
   Label if_index(this), if_unique_name(this), if_element_hole(this),
       if_oob(this), slow(this), stub_cache_miss(this),
-      if_property_dictionary(this), if_found_on_receiver(this),
-      lookup_prototype_chain(this);
+      if_property_dictionary(this), if_found_on_receiver(this);
 
   Node* receiver = p->receiver;
   GotoIf(TaggedIsSmi(receiver), &slow);
@@ -1529,8 +1528,7 @@ void AccessorAssembler::KeyedLoadICGeneric(const LoadICParameters* p) {
     Variable var_name_index(this, MachineType::PointerRepresentation());
     Label dictionary_found(this, &var_name_index);
     NameDictionaryLookup<NameDictionary>(properties, key, &dictionary_found,
-                                         &var_name_index,
-                                         &lookup_prototype_chain);
+                                         &var_name_index, &slow);
     Bind(&dictionary_found);
     {
       LoadPropertyFromNameDictionary(properties, var_name_index.value(),
@@ -1547,50 +1545,6 @@ void AccessorAssembler::KeyedLoadICGeneric(const LoadICParameters* p) {
     Return(value);
   }
 
-  Bind(&lookup_prototype_chain);
-  {
-    Variable var_holder_map(this, MachineRepresentation::kTagged);
-    Variable var_holder_instance_type(this, MachineRepresentation::kWord32);
-    Label return_undefined(this);
-    Variable* merged_variables[] = {&var_holder_map, &var_holder_instance_type};
-    Label loop(this, arraysize(merged_variables), merged_variables);
-
-    var_holder_map.Bind(receiver_map);
-    var_holder_instance_type.Bind(instance_type);
-    Goto(&loop);
-    Bind(&loop);
-    {
-      // Bailout if it can be an integer indexed exotic case.
-      GotoIf(Word32Equal(var_holder_instance_type.value(),
-                         Int32Constant(JS_TYPED_ARRAY_TYPE)),
-             &slow);
-      Node* proto = LoadMapPrototype(var_holder_map.value());
-      GotoIf(WordEqual(proto, NullConstant()), &return_undefined);
-      Node* proto_map = LoadMap(proto);
-      Node* proto_instance_type = LoadMapInstanceType(proto_map);
-      var_holder_map.Bind(proto_map);
-      var_holder_instance_type.Bind(proto_instance_type);
-      Label next_proto(this), return_value(this, &var_value), goto_slow(this);
-      TryGetOwnProperty(p->context, receiver, proto, proto_map,
-                        proto_instance_type, var_unique.value(), &return_value,
-                        &var_value, &next_proto, &goto_slow);
-
-      // This trampoline and the next are required to appease Turbofan's
-      // variable merging.
-      Bind(&next_proto);
-      Goto(&loop);
-
-      Bind(&goto_slow);
-      Goto(&slow);
-
-      Bind(&return_value);
-      Return(var_value.value());
-    }
-
-    Bind(&return_undefined);
-    Return(UndefinedConstant());
-  }
-
   Bind(&slow);
   {
     Comment("KeyedLoadGeneric_slow");