Selection should be updated after node is moved to another document

Source/core/editing/FrameSelection.cpp

 /*
  * Copyright (C) 2004, 2008, 2009, 2010 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 205 matching lines @@
 
     setSelection(newSelection, granularity);
 }
 
 void FrameSelection::setSelection(const VisibleSelection& newSelection, SetSelectionOptions options, CursorAlignOnScroll align, TextGranularity granularity)
 {
     bool closeTyping = options & CloseTyping;
     bool shouldClearTypingStyle = options & ClearTypingStyle;
     EUserTriggered userTriggered = selectionOptionsToUserTriggered(options);
 
-    VisibleSelection s = newSelection;
+    VisibleSelection s = validateSelection(newSelection);
     if (shouldAlwaysUseDirectionalSelection(m_frame))
         s.setIsDirectional(true);
 
     if (!m_frame) {
         m_selection = s;
         return;
     }
 
     // <http://bugs.webkit.org/show_bug.cgi?id=23464>: Infinite recursion at FrameSelection::setSelection
     // if document->frame() == m_frame we can get into an infinite loop
@@ skipping 1604 matching lines @@
 
 void FrameSelection::didChangeVisibleSelection()
 {
     ASSERT(m_observingVisibleSelection);
     // Invalidate the logical range when the underlying VisibleSelection has changed.
     m_logicalRange = nullptr;
     m_selection.clearChangeObserver();
     m_observingVisibleSelection = false;
 }
 
+VisibleSelection FrameSelection::validateSelection(const VisibleSelection& selection)
+{
+    if (!m_frame || selection.isNone())
+        return selection;
+
+    Position base = selection.base();
+    Position extent = selection.extent();
+    bool isBaseValid = base.document() == m_frame->document();
+    bool isExtentValid = extent.document() == m_frame->document();
+
+    if (isBaseValid && isExtentValid)
+        return selection;
+
+    VisibleSelection newSelection;
+    if (isBaseValid) {
+        newSelection.setWithoutValidation(base, base);
+    } else if (isExtentValid) {
+        newSelection.setWithoutValidation(extent, extent);
+    }
+    return newSelection;
+}
+
 void FrameSelection::startObservingVisibleSelectionChange()
 {
     ASSERT(!m_observingVisibleSelection);
     m_selection.setChangeObserver(*this);
     m_observingVisibleSelection = true;
 }
 
 void FrameSelection::stopObservingVisibleSelectionChangeIfNecessary()
 {
     if (m_observingVisibleSelection) {
@@ skipping 35 matching lines @@
     sel.showTreeForThis();
 }
 
 void showTree(const blink::FrameSelection* sel)
 {
     if (sel)
         sel->showTreeForThis();
 }
 
 #endif