Tag all prototypes as proto, except those set using __proto__

src/factory.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/factory.h"
 
 #include "src/allocation-site-scopes.h"
 #include "src/conversions.h"
 #include "src/isolate-inl.h"
 #include "src/macro-assembler.h"
@@ skipping 1271 matching lines @@
   // Allocate the function
   Handle<JSFunction> function = NewFunction(
       name, code, prototype, read_only_prototype);
 
   Handle<Map> initial_map = NewMap(
       type, instance_size, GetInitialFastElementsKind());
   if (prototype->IsTheHole() && !function->shared()->is_generator()) {
     prototype = NewFunctionPrototype(function);
   }
 
-  initial_map->set_prototype(*prototype);
-  JSFunction::SetInitialMap(function, initial_map);
+  JSFunction::SetInitialMap(function, initial_map,
+                            Handle<JSReceiver>::cast(prototype));
 
   return function;
 }
 
 
 Handle<JSFunction> Factory::NewFunction(Handle<String> name,
                                         Handle<Code> code,
                                         InstanceType type,
                                         int instance_size) {
   return NewFunction(name, code, the_hole_value(), type, instance_size);
@@ skipping 10 matching lines @@
     // properties.
     new_map = handle(native_context->generator_object_prototype_map());
   } else {
     // Each function prototype gets a fresh map to avoid unwanted sharing of
     // maps between prototypes of different constructors.
     Handle<JSFunction> object_function(native_context->object_function());
     DCHECK(object_function->has_initial_map());
     new_map = handle(object_function->initial_map());
   }
 
+  DCHECK(!new_map->is_prototype_map());
   Handle<JSObject> prototype = NewJSObjectFromMap(new_map);
 
   if (!function->shared()->is_generator()) {
     JSObject::AddProperty(prototype, constructor_string(), function, DONT_ENUM);
   }
 
   return prototype;
 }
 
 
@@ skipping 1031 matching lines @@
   return Handle<Object>::null();
 }
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return value ? true_value() : false_value();
 }
 
 
 } }  // namespace v8::internal