Support "once" event listener option

third_party/WebKit/Source/core/events/RegisteredEventListener.h

Index: third_party/WebKit/Source/core/events/RegisteredEventListener.h
diff --git a/third_party/WebKit/Source/core/events/RegisteredEventListener.h b/third_party/WebKit/Source/core/events/RegisteredEventListener.h
index db4d849efb58b5f14ee827144f5b58f44a0acbd0..ca809c59c40a16f3a77c06c6322ab9f1297ac3bc 100644
--- a/third_party/WebKit/Source/core/events/RegisteredEventListener.h
+++ b/third_party/WebKit/Source/core/events/RegisteredEventListener.h
@@ -36,6 +36,7 @@ public:
     RegisteredEventListener()
         : m_useCapture(false)
         , m_passive(false)
+        , m_once(false)
         , m_blockedEventWarningEmitted(false)
         , m_passiveForcedForDocumentTarget(false)
     {
@@ -45,6 +46,7 @@ public:
         : m_listener(listener)
         , m_useCapture(options.capture())
         , m_passive(options.passive())
+        , m_once(options.once())
         , m_blockedEventWarningEmitted(false)
         , m_passiveForcedForDocumentTarget(options.passiveForcedForDocumentTarget())
     {
@@ -61,6 +63,7 @@ public:
         result.setCapture(m_useCapture);
         result.setPassive(m_passive);
         result.setPassiveForcedForDocumentTarget(m_passiveForcedForDocumentTarget);
+        result.setOnce(m_once);
         return result;
     }
 
@@ -79,6 +82,11 @@ public:
         return m_passive;
     }
 
+    bool once() const
+    {
+        return m_once;
+    }
+
     bool capture() const
     {
         return m_useCapture;
@@ -119,6 +127,7 @@ private:
     Member<EventListener> m_listener;
     unsigned m_useCapture : 1;
     unsigned m_passive : 1;
+    unsigned m_once : 1;
     unsigned m_blockedEventWarningEmitted : 1;
     unsigned m_passiveForcedForDocumentTarget : 1;
 };