Return null when no promise/reason is given in PromiseRejectionEvent

Source/bindings/core/v8/custom/V8PromiseRejectionEventCustom.cpp

+// Copyright 2015 The Chromium 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 "config.h"
+#include "bindings/core/v8/V8PromiseRejectionEvent.h"
+
+#include "bindings/core/v8/DOMWrapperWorld.h"
+#include "bindings/core/v8/ScriptPromise.h"
+#include "bindings/core/v8/ScriptState.h"
+#include "bindings/core/v8/ScriptValue.h"
+#include "bindings/core/v8/V8Binding.h"
+
+namespace blink {
+
+void V8PromiseRejectionEvent::promiseAttributeGetterCustom(const v8::PropertyCallbackInfo<v8::Value>& info)
+{
+    v8::Isolate* isolate = info.GetIsolate();
+    PromiseRejectionEvent* event = V8PromiseRejectionEvent::toImpl(info.Holder());
+    ScriptPromise promise = event->promise();
+    if (promise.isEmpty() || promise.scriptValue().scriptState()->world().worldId() != ScriptState::current(isolate)->world().worldId()) {

[haraken, 2015/06/19 12:17:32]

Sorry for an iterative comment...

By moving this check into PromiseRejectionEvent::promise(), can we get rid of
the custom binding? In other words, if PromiseRejectionEvent::promise() is
implemented in a way that returns a valid ScriptPromise only for the same world,
we won't need this custom binding.

+        // Return null when the promise is accessed by a different world than the world that created the promise.
+        v8SetReturnValue(info, v8::Null(isolate));
+        return;
+    }
+
+    v8SetReturnValue(info, promise.v8Value());
+}
+
+void V8PromiseRejectionEvent::reasonAttributeGetterCustom(const v8::PropertyCallbackInfo<v8::Value>& info)
+{
+    v8::Isolate* isolate = info.GetIsolate();
+    PromiseRejectionEvent* event = V8PromiseRejectionEvent::toImpl(info.Holder());
+    ScriptValue reason = event->reason();
+    if (reason.isEmpty() || reason.scriptState()->world().worldId() != ScriptState::current(isolate)->world().worldId()) {
+        // Return null when the value is accessed by a different world than the world that created the value.
+        v8SetReturnValue(info, v8::Null(isolate));
+        return;
+    }
+
+    v8SetReturnValue(info, reason.v8Value());
+}
+
+} // namespace blink