Remove custom code for MessageEvent.ports getter

Source/core/dom/MessageEvent.h

Index: Source/core/dom/MessageEvent.h
diff --git a/Source/core/dom/MessageEvent.h b/Source/core/dom/MessageEvent.h
index 297a7883b1ab117cfbff169318c23663f28fb729..5912f8ff0cb9c1bd5cf9e37341c0d7fef00a80d6 100644
--- a/Source/core/dom/MessageEvent.h
+++ b/Source/core/dom/MessageEvent.h
@@ -88,7 +88,7 @@ public:
     const String& origin() const { return m_origin; }
     const String& lastEventId() const { return m_lastEventId; }
     DOMWindow* source() const { return m_source.get(); }
-    MessagePortArray* ports() const { return m_ports.get(); }
+    MessagePortArray ports() const { return m_ports ? *m_ports : MessagePortArray(); }
 
     virtual const AtomicString& interfaceName() const;