Revert of [snapshot] Move builtins generation into mksnapshot

test/cctest/setup-isolate-for-tests.h

-// Copyright 2017 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.
-
-#include "src/setup-isolate.h"
-
-namespace v8 {
-namespace internal {
-
-class SetupIsolateDelegateForTests : public SetupIsolateDelegate {
- public:
-  SetupIsolateDelegateForTests() : SetupIsolateDelegate() {}
-  virtual ~SetupIsolateDelegateForTests() {}
-
-  void SetupBuiltins(Isolate* isolate, bool create_heap_objects) override;
-
-  void SetupInterpreter(interpreter::Interpreter* interpreter,
-                        bool create_heap_objects) override;
-};
-
-}  // namespace internal
-}  // namespace v8