Clamp scroll offset to min/max in PopupListBox::updateScrollbars.

Source/web/PopupListBox.cpp

 /*
  * Copyright (c) 2011, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 948 matching lines @@
     // NOTE: Unlike FrameView we do not need to incorporate any scaling factor,
     // and there is only one scrollbar to exclude.
     IntSize size = frameRect().size();
     Scrollbar* verticalBar = verticalScrollbar();
     if (scrollbarInclusion == ExcludeScrollbars && verticalBar && !verticalBar->isOverlayScrollbar()) {
         size.setWidth(std::max(0, size.width() - verticalBar->width()));
     }
     return IntRect(m_scrollOffset, size);
 }
 
-void PopupListBox::updateScrollbars(const IntPoint& desiredOffset)
+void PopupListBox::updateScrollbars(IntPoint desiredOffset)
 {
     IntSize oldVisibleSize = visibleContentRect().size();
     adjustScrollbarExistence();
     updateScrollbarGeometry();
     IntSize newVisibleSize = visibleContentRect().size();
 
     if (newVisibleSize.width() > oldVisibleSize.width()) {
         if (shouldPlaceVerticalScrollbarOnLeft())
             invalidateRect(IntRect(0, 0, newVisibleSize.width() - oldVisibleSize.width(), newVisibleSize.height()));
         else
             invalidateRect(IntRect(oldVisibleSize.width(), 0, newVisibleSize.width() - oldVisibleSize.width(), newVisibleSize.height()));
     }
+
+    desiredOffset = desiredOffset.shrunkTo(maximumScrollPosition());
+    desiredOffset = desiredOffset.expandedTo(minimumScrollPosition());
+
     if (desiredOffset != scrollPosition())
         ScrollableArea::scrollToOffsetWithoutAnimation(desiredOffset);
 }
 
 void PopupListBox::adjustScrollbarExistence()
 {
     bool needsVerticalScrollbar = contentsSize().height() > visibleHeight();
     if (!!m_verticalScrollbar != needsVerticalScrollbar) {
         setHasVerticalScrollbar(needsVerticalScrollbar);
         contentsResized();
@@ skipping 63 matching lines @@
     maximumOffset.clampNegativeToZero();
     return maximumOffset;
 }
 
 IntPoint PopupListBox::minimumScrollPosition() const
 {
     return IntPoint(-scrollOrigin().x(), -scrollOrigin().y());
 }
 
 } // namespace blink