Correctly track lifetime of promise rejection events

Source/core/events/PromiseRejectionEvent.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 "core/events/PromiseRejectionEvent.h"
 
 #include "bindings/core/v8/DOMWrapperWorld.h"
 
@@ skipping 30 matching lines @@
 }
 
 ScriptValue PromiseRejectionEvent::reason(ScriptState* state) const
 {
     // Return null when the value is accessed by a different world than the world that created the value.
     if (m_reason.isEmpty() || !m_scriptState || !m_scriptState->contextIsValid() || m_scriptState->world().worldId() != state->world().worldId())
         return ScriptValue(state, v8::Null(state->isolate()));
     return ScriptValue(m_scriptState.get(), m_reason.newLocal(m_scriptState->isolate()));
 }
 
+void PromiseRejectionEvent::setWrapperReference(v8::Isolate* isolate, const v8::Persistent<v8::Object>& wrapper)
+{
+    if (!m_promise.isEmpty())
+        m_promise.setReference(wrapper, isolate);

[haraken, 2015/06/29 07:26:53]

This reference can be a cross-world reference. Would you add a comment on why it
is ok here?

+    if (!m_reason.isEmpty())
+        m_reason.setReference(wrapper, isolate);
+}
+
 const AtomicString& PromiseRejectionEvent::interfaceName() const
 {
     return EventNames::PromiseRejectionEvent;
 }
 
 DEFINE_TRACE(PromiseRejectionEvent)
 {
     Event::trace(visitor);
 }
 
 void PromiseRejectionEvent::didCollectPromise(const v8::WeakCallbackInfo<PromiseRejectionEvent>& data)
 {
     data.GetParameter()->m_promise.clear();
 }
 
 void PromiseRejectionEvent::didCollectReason(const v8::WeakCallbackInfo<PromiseRejectionEvent>& data)
 {
     data.GetParameter()->m_reason.clear();
 }
 
 } // namespace blink