[es6] Partially implement Reflect.preventExtensions.

src/objects.h

 // 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 1847 matching lines @@
                                         PropertyDescriptor* desc,
                                         ShouldThrow should_throw);
 
   static bool GetOwnPropertyDescriptor(Isolate* isolate,
                                        Handle<JSObject> object,
                                        Handle<Object> key,
                                        PropertyDescriptor* desc);
   static bool GetOwnPropertyDescriptor(LookupIterator* it,
                                        PropertyDescriptor* desc);
 
+  // Disallow further properties to be added to the object.  This is
+  // ES6's [[PreventExtensions]] when passed DONT_THROW.
+  MUST_USE_RESULT static Maybe<bool> PreventExtensions(
+      Handle<JSReceiver> object, ShouldThrow should_throw);
+
   // Tests for the fast common case for property enumeration.
   bool IsSimpleEnum();
 
   // Returns the class name ([[Class]] property in the specification).
   String* class_name();
 
   // Returns the constructor name (the name (possibly, inferred name) of the
   // function that was used to instantiate the object).
   String* constructor_name();
 
@@ skipping 439 matching lines @@
   // pre_allocated_value and the rest with filler_value.
   // Note: this call does not update write barrier, the caller is responsible
   // to ensure that |filler_value| can be collected without WB here.
   inline void InitializeBody(Map* map,
                              Object* pre_allocated_value,
                              Object* filler_value);
 
   // Check whether this object references another object
   bool ReferencesObject(Object* obj);
 
-  // Disallow further properties to be added to the oject.
-  MUST_USE_RESULT static Maybe<bool> PreventExtensionsInternal(
-      Handle<JSObject> object);  // ES [[PreventExtensions]]
-  MUST_USE_RESULT static MaybeHandle<Object> PreventExtensions(
-      Handle<JSObject> object);  // ES Object.preventExtensions
+  MUST_USE_RESULT static Maybe<bool> PreventExtensions(
+      Handle<JSObject> object, ShouldThrow should_throw);
 
   static bool IsExtensible(Handle<JSObject> object);
 
   // ES5 Object.seal
   MUST_USE_RESULT static MaybeHandle<Object> Seal(Handle<JSObject> object);
 
   // ES5 Object.freeze
   MUST_USE_RESULT static MaybeHandle<Object> Freeze(Handle<JSObject> object);
 
   // Called the first time an object is observed with ES7 Object.observe.
@@ skipping 168 matching lines @@
 
   static Handle<Smi> GetOrCreateIdentityHash(Handle<JSObject> object);
 
   static Handle<SeededNumberDictionary> GetNormalizedElementDictionary(
       Handle<JSObject> object, Handle<FixedArrayBase> elements);
 
   // Helper for fast versions of preventExtensions, seal, and freeze.
   // attrs is one of NONE, SEALED, or FROZEN (depending on the operation).
   template <PropertyAttributes attrs>
   MUST_USE_RESULT static Maybe<bool> PreventExtensionsWithTransition(
-      Handle<JSObject> object);
+      Handle<JSObject> object, ShouldThrow should_throw);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSObject);
 };
 
 
 // Common superclass for FixedArrays that allow implementations to share
 // common accessors and some code paths.
 class FixedArrayBase: public HeapObject {
  public:
   // [length]: length of the array.
@@ skipping 8249 matching lines @@
   // (elements + properties) in the current level.
   int levelLength_;
 
   DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
 };
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_