diff --git a/Source/WebCore/platform/ScrollableArea.h b/Source/WebCore/platform/ScrollableArea.h
index e919cee..36131fd 100644
--- a/Source/WebCore/platform/ScrollableArea.h
+++ b/Source/WebCore/platform/ScrollableArea.h
@@ -136,6 +136,8 @@
     virtual bool shouldSuspendScrollAnimations() const { return true; }
     virtual void scrollbarStyleChanged() { }
     virtual void setVisibleScrollerThumbRect(const IntRect&) { }
+
+    virtual bool isOnActivePage() const { ASSERT_NOT_REACHED(); return true; }
     
     bool isHorizontalScrollerPinnedToMinimumPosition() const { return !horizontalScrollbar() || scrollPosition(horizontalScrollbar()) <= minimumScrollPosition().x(); }
     bool isHorizontalScrollerPinnedToMaximumPosition() const { return !horizontalScrollbar() || scrollPosition(horizontalScrollbar()) >= maximumScrollPosition().x(); }