Use instance type in Object.prototype.toString().

src/heap/heap.cc

 // Copyright 2012 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/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 3535 matching lines @@
   DCHECK(!allocation.To(&obj) || !obj->IsJSGlobalObject());
 #endif
   return allocation;
 }
 
 
 AllocationResult Heap::CopyJSObject(JSObject* source, AllocationSite* site) {
   // Make the clone.
   Map* map = source->map();
 
-  // We can only clone regexps, normal objects, api objects or arrays. Copying
-  // anything else will break invariants.
+  // We can only clone regexps, normal objects, api objects, errors or arrays.
+  // Copying anything else will break invariants.
   CHECK(map->instance_type() == JS_REGEXP_TYPE ||
         map->instance_type() == JS_OBJECT_TYPE ||
+        map->instance_type() == JS_ERROR_TYPE ||
         map->instance_type() == JS_ARRAY_TYPE ||
         map->instance_type() == JS_API_OBJECT_TYPE ||
         map->instance_type() == JS_SPECIAL_API_OBJECT_TYPE);
 
   int object_size = map->instance_size();
   HeapObject* clone = nullptr;
 
   DCHECK(site == NULL || AllocationSite::CanTrack(map->instance_type()));
 
   int adjusted_object_size =
@@ skipping 2809 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8