[es6] Implement spec compliant ToPrimitive in the runtime.

src/messages.cc

 // Copyright 2011 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/messages.h"
 
 #include "src/api.h"
 #include "src/execution.h"
 #include "src/string-builder.h"
 
@@ skipping 453 matching lines @@
 
 MaybeHandle<String> ErrorToStringHelper::GetStringifiedProperty(
     Isolate* isolate, LookupIterator* property_lookup,
     Handle<String> default_value) {
   if (!property_lookup->IsFound()) return default_value;
   Handle<Object> obj;
   ASSIGN_RETURN_ON_EXCEPTION(isolate, obj, Object::GetProperty(property_lookup),
                              String);
   if (obj->IsUndefined()) return default_value;
   if (!obj->IsString()) {
-    ASSIGN_RETURN_ON_EXCEPTION(isolate, obj, Execution::ToString(isolate, obj),
+    ASSIGN_RETURN_ON_EXCEPTION(isolate, obj, Object::ToString(isolate, obj),
                                String);
   }
   return Handle<String>::cast(obj);
 }
 
 }  // namespace internal
 }  // namespace v8