VisibleSelection::nonBoundaryShadowTreeRootNode should return null when its anchor is a shadow root

Source/core/editing/VisibleSelection.cpp

 /*
  * Copyright (C) 2004, 2005, 2006 Apple Computer, 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 734 matching lines @@
     return isRichlyEditablePosition(start());
 }
 
 Element* VisibleSelection::rootEditableElement() const
 {
     return editableRootForPosition(start());
 }
 
 Node* VisibleSelection::nonBoundaryShadowTreeRootNode() const
 {
-    return start().deprecatedNode() ? start().deprecatedNode()->nonBoundaryShadowTreeRootNode() : 0;
+    return start().deprecatedNode() && !start().deprecatedNode()->isShadowRoot() ? start().deprecatedNode()->nonBoundaryShadowTreeRootNode() : 0;

[yosin_UTC9, 2015/01/14 01:33:44]

I think |start()| should not point to shadow root. It seems selection adjust
code after node removal made this. So, it is better to change adjust code.

[keishi, 2015/01/14 05:04:51]

I have confirmed that this is what's happening.
1. JS code sets selection to <input type=text>'s UA shadow editor element.
(input1.setSelectionRange(0))
2. input1's type is changed to 'week'.
3. TextFieldInputType::destroyShadowSubtree
4. FrameSelection::nodeWillBeRemoved
5. FrameSelection::respondToNodeModification
6. positionInParentBeforeNode returns the UA shadow root (because it is the
parent of the editor element) which is then set to the VisualSelection::m_start.

How should this work? Where should the selection go when all the elements in the
UA shadow root is removed? Should positionInParentBeforeNode return the shadow
host element instead of the shadow root?

 }
 
 VisibleSelection::ChangeObserver::ChangeObserver()
 {
 }
 
 VisibleSelection::ChangeObserver::~ChangeObserver()
 {
 }
 
@@ skipping 110 matching lines @@
     sel.showTreeForThis();
 }
 
 void showTree(const blink::VisibleSelection* sel)
 {
     if (sel)
         sel->showTreeForThis();
 }
 
 #endif