Oilpan: Remove a visitor parameter from isHeapObjectAlive

Source/modules/mediastream/RTCDataChannel.cpp

Index: Source/modules/mediastream/RTCDataChannel.cpp
diff --git a/Source/modules/mediastream/RTCDataChannel.cpp b/Source/modules/mediastream/RTCDataChannel.cpp
index 2fb38e7f52c9e8bdcdd43a7441f2c518b0ba7655..d380bcb953df240f7430ebf2ca2712dda7399843 100644
--- a/Source/modules/mediastream/RTCDataChannel.cpp
+++ b/Source/modules/mediastream/RTCDataChannel.cpp
@@ -326,7 +326,7 @@ void RTCDataChannel::scheduledEventTimerFired(Timer<RTCDataChannel>*)
 
 void RTCDataChannel::clearWeakMembers(Visitor* visitor)
 {
-    if (visitor->isHeapObjectAlive(m_connection))
+    if (Heap::isHeapObjectAlive(m_connection))
         return;
     stop();
     m_connection = nullptr;