[runtime] Share constructor/non-constructor bound function maps.

src/runtime/runtime-function.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/runtime/runtime-utils.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/compiler.h"
 #include "src/deoptimizer.h"
@@ skipping 391 matching lines @@
     new_bindings->set_binding(out_index, *arguments[j + 1]);
   }
   new_bindings->set_map_no_write_barrier(isolate->heap()->fixed_array_map());
   bound_function->set_function_bindings(*new_bindings);
 
   // Update length. Have to remove the prototype first so that map migration
   // is happy about the number of fields.
   RUNTIME_ASSERT(bound_function->RemovePrototype());
 
   // The new function should have the same [[Prototype]] as the bindee.
-  Handle<Map> bound_function_map(
-      isolate->native_context()->bound_function_map());
+  Handle<Map> bound_function_map =
+      bindee->IsConstructor()
+          ? isolate->bound_function_with_constructor_map()
+          : isolate->bound_function_without_constructor_map();
   PrototypeIterator iter(isolate, bindee);
   Handle<Object> proto = PrototypeIterator::GetCurrent(iter);
   if (bound_function_map->prototype() != *proto) {
     bound_function_map = Map::TransitionToPrototype(bound_function_map, proto,
                                                     REGULAR_PROTOTYPE);
   }
-  if (bound_function_map->is_constructor() != bindee->IsConstructor()) {
-    bound_function_map = Map::Copy(bound_function_map, "IsConstructor");
-    bound_function_map->set_is_constructor(bindee->IsConstructor());
-  }
   JSObject::MigrateToMap(bound_function, bound_function_map);
+  DCHECK_EQ(bindee->IsConstructor(), bound_function->IsConstructor());
 
   Handle<String> length_string = isolate->factory()->length_string();
   // These attributes must be kept in sync with how the bootstrapper
   // configures the bound_function_map retrieved above.
   // We use ...IgnoreAttributes() here because of length's read-onliness.
   PropertyAttributes attr =
       static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY);
   RETURN_FAILURE_ON_EXCEPTION(
       isolate, JSObject::SetOwnPropertyIgnoreAttributes(
                    bound_function, length_string, new_length, attr));
@@ skipping 164 matching lines @@
 
 
 RUNTIME_FUNCTION(Runtime_ThrowStrongModeTooFewArguments) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 0);
   THROW_NEW_ERROR_RETURN_FAILURE(isolate,
                                  NewTypeError(MessageTemplate::kStrongArity));
 }
 }  // namespace internal
 }  // namespace v8