Correctly track lifetime of promise rejection events

Source/core/events/PromiseRejectionEvent.cpp

Index: Source/core/events/PromiseRejectionEvent.cpp
diff --git a/Source/core/events/PromiseRejectionEvent.cpp b/Source/core/events/PromiseRejectionEvent.cpp
index a688ca8c088e0902764ae9b39fef9165953f1f70..b0461d8a7671174e6c49aef864f4ba43e4d8f5c7 100644
--- a/Source/core/events/PromiseRejectionEvent.cpp
+++ b/Source/core/events/PromiseRejectionEvent.cpp
@@ -48,6 +48,14 @@ ScriptValue PromiseRejectionEvent::reason(ScriptState* state) const
     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;