Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/events/GestureEvent.cpp

Index: Source/core/events/GestureEvent.cpp
diff --git a/Source/core/events/GestureEvent.cpp b/Source/core/events/GestureEvent.cpp
index 5c7e9372d7914dfebafab8e57f12519fb12b4540..d8e5ca187a3d1d389de6dfbf29ff4f7f9f18e24d 100644
--- a/Source/core/events/GestureEvent.cpp
+++ b/Source/core/events/GestureEvent.cpp
@@ -63,7 +63,7 @@ PassRefPtr<GestureEvent> GestureEvent::create(PassRefPtr<AbstractView> view, con
     case PlatformEvent::GesturePinchUpdate:
     case PlatformEvent::GestureTapDownCancel:
     default:
-        return 0;
+        return nullptr;
     }
     return adoptRef(new GestureEvent(eventType, view, event.globalPosition().x(), event.globalPosition().y(), event.position().x(), event.position().y(), event.ctrlKey(), event.altKey(), event.shiftKey(), event.metaKey(), deltaX, deltaY));
 }