Reland: Extend IsExtensible proxy trap fast path for Reflect.isExtensible

This is reland of Ib1c3f78d1f1a44c6628d351fed3bcdc91ca08cb5
Just fix lint error for unused arguments in Torque.

> Original commit message:

> The fast path for IsExtensible proxy trap is already implemented, we just need to use this for ReflectIsExtensible.
Now, ReflectIsExtensible is now a Torque builtin (previously CPP). Other cases will fall back to runtime.

> Bug: v8:6664
> Change-Id: Ib1c3f78d1f1a44c6628d351fed3bcdc91ca08cb5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1645438
> Reviewed-by: Maya Lekova <mslekova@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Tamer Tas <tmrts@chromium.org>
> Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
> Cr-Commit-Position: refs/heads/master@{#62031}

Bug: v8:6664
Change-Id: If44ac321ce712a969b3f5076411573eb3968cc14
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1646900
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62070}

BUILD.gn

@@ -962,6 +962,7 @@ torque_files = [
   "src/builtins/proxy-revoke.tq",
   "src/builtins/proxy-set-property.tq",
   "src/builtins/proxy.tq",
+  "src/builtins/reflect.tq",
   "src/builtins/regexp-replace.tq",
   "src/builtins/regexp.tq",
   "src/builtins/string.tq",
@@ -3295,7 +3296,7 @@ v8_source_set("v8_crash_keys") {
     ]
   }
 
-configs = [ ":internal_config" ]
+  configs = [ ":internal_config" ]
 }
 
 group("v8_base") {

src/builtins/builtins-definitions.h

@@ -827,7 +827,6 @@ namespace internal {
   CPP(ReflectGetOwnPropertyDescriptor)                                         \
   CPP(ReflectGetPrototypeOf)                                                   \
   TFJ(ReflectHas, 2, kReceiver, kTarget, kKey)                                 \
-  CPP(ReflectIsExtensible)                                                     \
   CPP(ReflectOwnKeys)                                                          \
   CPP(ReflectPreventExtensions)                                                \
   CPP(ReflectSet)                                                              \

src/builtins/builtins-reflect.cc

@@ -136,25 +136,6 @@ BUILTIN(ReflectGetPrototypeOf) {
                            JSReceiver::GetPrototype(isolate, receiver));
 }
 
-// ES6 section 26.1.10 Reflect.isExtensible
-BUILTIN(ReflectIsExtensible) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(2, args.length());
-  Handle<Object> target = args.at(1);
-
-  if (!target->IsJSReceiver()) {
-    THROW_NEW_ERROR_RETURN_FAILURE(
-        isolate, NewTypeError(MessageTemplate::kCalledOnNonObject,
-                              isolate->factory()->NewStringFromAsciiChecked(
-                                  "Reflect.isExtensible")));
-  }
-
-  Maybe<bool> result =
-      JSReceiver::IsExtensible(Handle<JSReceiver>::cast(target));
-  MAYBE_RETURN(result, ReadOnlyRoots(isolate).exception());
-  return *isolate->factory()->ToBoolean(result.FromJust());
-}
-
 // ES6 section 26.1.11 Reflect.ownKeys
 BUILTIN(ReflectOwnKeys) {
   HandleScope scope(isolate);

src/builtins/reflect.tq

+// 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.
+
+namespace reflect {
+
+  const kCalledOnNonObject: constexpr MessageTemplate
+  generates 'MessageTemplate::kCalledOnNonObject';
+
+  // ES6 section 26.1.10 Reflect.isExtensible
+  transitioning javascript builtin ReflectIsExtensible(
+      implicit context: Context)(_receiver: Object, object: Object): Object {
+    const objectJSReceiver = Cast<JSReceiver>(object)
+        otherwise ThrowTypeError(kCalledOnNonObject, 'Reflect.isExtensible');
+    return object::ObjectIsExtensible(objectJSReceiver);
+  }
+}  // namespace reflect