[CSA][cleanup] Use Name instead of String type for var_name in KeyedLoadICGeneric.

BUG=v8:6949,v8:9396,chromium:1004912

Change-Id: Ifa8207283aadad258281bffda6d49da574402a24
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1809370
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Auto-Submit: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63865}

src/ic/accessor-assembler.cc

@@ -3007,7 +3007,7 @@ void AccessorAssembler::KeyedLoadICGeneric(const LoadICParameters* p) {
     }
 
     {
-      TVARIABLE(String, var_name);
+      TVARIABLE(Name, var_name);
 
       BIND(&if_other);
       {
@@ -3019,6 +3019,7 @@ void AccessorAssembler::KeyedLoadICGeneric(const LoadICParameters* p) {
 
       BIND(&if_notunique);
       {
+        // Try to make it unique by internalizing.
         var_name = CAST(p->name());
         Goto(&maybe_internalize_on_the_fly);
       }
@@ -3031,7 +3032,7 @@ void AccessorAssembler::KeyedLoadICGeneric(const LoadICParameters* p) {
           // invariant doesn't hold with named property interceptors (at this
           // point), so we take the {if_runtime} path instead.
           Label if_in_string_table(this);
-          TryInternalizeString(var_name.value(), &if_index, &var_index,
+          TryInternalizeString(CAST(var_name.value()), &if_index, &var_index,
                                &if_in_string_table, &var_unique, &if_runtime,
                                &if_runtime);
 

test/mjsunit/regress/regress-1004912.js

+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var key = {
+  toString() {
+    return Symbol();
+  }
+};
+
+var obj = {};
+obj[key];