Fix ArrayLengthSetter to not throw on non-extensible receivers.

src/accessors.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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/compiler.h"
 #include "src/contexts.h"
@@ skipping 156 matching lines @@
   info.GetReturnValue().Set(Utils::ToLocal(Handle<Object>(result, isolate)));
 }
 
 
 void Accessors::ArrayLengthSetter(
     v8::Local<v8::String> name,
     v8::Local<v8::Value> val,
     const v8::PropertyCallbackInfo<void>& info) {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(info.GetIsolate());
   HandleScope scope(isolate);
-  Handle<JSObject> object = Handle<JSObject>::cast(
-      Utils::OpenHandle(*info.This()));
+  Handle<JSObject> object = Utils::OpenHandle(*info.This());
   Handle<Object> value = Utils::OpenHandle(*val);
   // This means one of the object's prototypes is a JSArray and the
   // object does not have a 'length' property.  Calling SetProperty
   // causes an infinite loop.
   if (!object->IsJSArray()) {
+    // This behaves sloppy since we lost the actual strict-mode.
+    // TODO(verwaest): Fix by making ExecutableAccessorInfo behave like data
+    // properties.
+    if (!object->map()->is_extensible()) return;
     MaybeHandle<Object> maybe_result = JSObject::SetOwnPropertyIgnoreAttributes(
         object, isolate->factory()->length_string(), value, NONE);
     maybe_result.Check();
     return;
   }
 
   value = FlattenNumber(isolate, value);
 
   Handle<JSArray> array_handle = Handle<JSArray>::cast(object);
   MaybeHandle<Object> maybe;
@@ skipping 1157 matching lines @@
   info->set_data(Smi::FromInt(index));
   Handle<Object> getter = v8::FromCData(isolate, &ModuleGetExport);
   Handle<Object> setter = v8::FromCData(isolate, &ModuleSetExport);
   info->set_getter(*getter);
   if (!(attributes & ReadOnly)) info->set_setter(*setter);
   return info;
 }
 
 
 } }  // namespace v8::internal