[es6] don't "replace" Object.prototype.toString for --harmony-tostring

src/bootstrapper.cc

 // Copyright 2014 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/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
@@ skipping 1671 matching lines @@
 
 #define EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(id) \
   void Genesis::InitializeGlobal_##id() {}
 
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_modules)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_arrays)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_array_includes)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_classes)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_object_literals)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_arrow_functions)
-EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_tostring)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_proxies)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_sloppy)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_unicode)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_computed_property_names)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_rest_parameters)
 
 void Genesis::InitializeGlobal_harmony_regexps() {
   Handle<JSObject> builtins(native_context()->builtins());
 
   Handle<HeapObject> flag(FLAG_harmony_regexps ? heap()->true_value()
@@ skipping 50 matching lines @@
   Handle<JSGlobalObject> global(JSGlobalObject::cast(
       native_context()->global_object()));
   Handle<String> reflect_string =
       factory()->NewStringFromStaticChars("Reflect");
   Handle<Object> reflect =
       factory()->NewJSObject(isolate()->object_function(), TENURED);
   JSObject::AddProperty(global, reflect_string, reflect, DONT_ENUM);
 }
 
 
+void Genesis::InitializeGlobal_harmony_tostring() {
+  Handle<JSObject> builtins(native_context()->builtins());
+
+  Handle<HeapObject> flag(FLAG_harmony_tostring ? heap()->true_value()
+                                                : heap()->false_value());
+  Runtime::SetObjectProperty(isolate(), builtins,
+                             factory()->harmony_tostring_string(), flag,
+                             STRICT).Assert();
+}
+
+
 Handle<JSFunction> Genesis::InstallInternalArray(
     Handle<JSBuiltinsObject> builtins,
     const char* name,
     ElementsKind elements_kind) {
   // --- I n t e r n a l   A r r a y ---
   // An array constructor on the builtins object that works like
   // the public Array constructor, except that its prototype
   // doesn't inherit from Object.prototype.
   // To be used only for internal work by builtins. Instances
   // must not be leaked to user code.
@@ skipping 1191 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 } }  // namespace v8::internal