[strong] Implement per-object restrictions behaviour for prototype setting

src/objects.cc

 // Copyright 2013 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 <iomanip>
 #include <sstream>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 12588 matching lines @@
 
 
 MaybeHandle<Object> JSObject::SetPrototype(Handle<JSObject> object,
                                            Handle<Object> value,
                                            bool from_javascript) {
 #ifdef DEBUG
   int size = object->Size();
 #endif
 
   Isolate* isolate = object->GetIsolate();
+  // Strong objects may not have their prototype set via __proto__ or
+  // setPrototypeOf.
+  if (from_javascript && object->map()->is_strong()) {
+    THROW_NEW_ERROR(isolate,
+                    NewTypeError(MessageTemplate::kStrongSetProto, object),
+                    Object);
+  }
   Heap* heap = isolate->heap();
   // Silently ignore the change if value is not a JSObject or null.
   // SpiderMonkey behaves this way.
   if (!value->IsJSReceiver() && !value->IsNull()) return value;
 
   // From 8.6.2 Object Internal Methods
   // ...
   // In addition, if [[Extensible]] is false the value of the [[Class]] and
   // [[Prototype]] internal properties of the object may not be modified.
   // ...
@@ skipping 4634 matching lines @@
 void PropertyCell::SetValueWithInvalidation(Handle<PropertyCell> cell,
                                             Handle<Object> new_value) {
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 } }  // namespace v8::internal