Merge 78431 - Some Scrollbar functions assume an attached ScrollableArea but ...

Source/WebCore/platform/Scrollbar.cpp

Index: Source/WebCore/platform/Scrollbar.cpp
===================================================================
--- Source/WebCore/platform/Scrollbar.cpp	(revision 78504)
+++ Source/WebCore/platform/Scrollbar.cpp	(working copy)
@@ -196,7 +196,7 @@
     }
 
     // Handle the arrows and track.
-    if (scrollableArea()->scroll(pressedPartScrollDirection(), pressedPartScrollGranularity()))
+    if (m_scrollableArea && m_scrollableArea->scroll(pressedPartScrollDirection(), pressedPartScrollGranularity()))
         startTimerIfNeeded(delay);
 }
 
@@ -268,7 +268,8 @@
     
     if (delta) {
         float newPosition = static_cast<float>(thumbPos + delta) * maximum() / (trackLen - thumbLen);
-        scrollableArea()->scrollToOffsetWithoutAnimation(m_orientation, newPosition);
+        if (m_scrollableArea)
+            m_scrollableArea->scrollToOffsetWithoutAnimation(m_orientation, newPosition);
     }
 }
 
@@ -300,9 +301,10 @@
 bool Scrollbar::mouseMoved(const PlatformMouseEvent& evt)
 {
     if (m_pressedPart == ThumbPart) {
-        if (theme()->shouldSnapBackToDragOrigin(this, evt))
-            scrollableArea()->scrollToOffsetWithoutAnimation(m_orientation, m_dragOrigin);
-        else {
+        if (theme()->shouldSnapBackToDragOrigin(this, evt)) {
+            if (m_scrollableArea)
+                m_scrollableArea->scrollToOffsetWithoutAnimation(m_orientation, m_dragOrigin);
+        } else {
             moveThumb(m_orientation == HorizontalScrollbar ? 
                       convertFromContainingWindow(evt.pos()).x() :
                       convertFromContainingWindow(evt.pos()).y());