Make RemoveFormat command to work with mixed editable

Source/core/editing/ApplyStyleCommand.cpp

 /*
  * Copyright (C) 2005, 2006, 2008, 2009 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 1137 matching lines @@
             if (isStyledInlineElementToRemove(elem.get())) {
                 styleToPushDown = EditingStyle::create();
                 childNode = elem->firstChild();
             }
 
             removeInlineStyleFromElement(style, elem.get(), RemoveIfNeeded, styleToPushDown.get());
             if (!elem->inDocument()) {
                 if (s.deprecatedNode() == elem) {
                     // Since elem must have been fully selected, and it is at the start
                     // of the selection, it is clear we can set the new s offset to 0.
-                    ASSERT(s.anchorType() == Position::PositionIsBeforeAnchor || s.offsetInContainerNode() <= 0);
+                    ASSERT(s.anchorType() == Position::PositionIsBeforeAnchor || s.anchorType() == Position::PositionIsBeforeChildren || s.offsetInContainerNode() <= 0);

[Yuta Kitamura, 2014/07/01 09:12:35]

Who creates the position of type PositionIsBeforeChildren? It's possible
that the creator of the position is to blame, instead of this assertion.

[yosin_UTC9, 2014/07/02 03:30:36]

In the attached test case, |firstPositionInOrBeforeNode(next.get())|, L1159=just
below assertion, returns 
|PositionIsBeforeChildren| for B element.

Here is definition of |firstPositionInOrBeforeNode|
inline Position firstPositionInOrBeforeNode(Node* node)
{
    if (!node)
        return Position();
    return editingIgnoresContent(node) ? positionBeforeNode(node) :
firstPositionInNode(node);
}

[Yuta Kitamura, 2014/07/02 07:27:21]

I don't understand your reasoning. This ASSERT is located
before the assignment at line 1159. How does that affect
the value of |s.anchorType()| at line 1158?

[yosin_UTC9, 2014/07/02 08:04:03]

The ASSERT and firstPositionInOrBeforeNode() is in while loop. |s| is updated
here and checked in next iteration.

[Yuta Kitamura, 2014/07/03 05:11:29]

Okay, I think this is an oversight from rniwa's change
<https://chromium.googlesource.com/chromium/blink/+/0db51d7c3a2245cb7b99c6956f...>.

                     s = firstPositionInOrBeforeNode(next.get());
                 }
                 if (e.deprecatedNode() == elem) {
                     // Since elem must have been fully selected, and it is at the end
                     // of the selection, it is clear we can set the new e offset to
                     // the max range offset of prev.
                     ASSERT(s.anchorType() == Position::PositionIsAfterAnchor || !offsetIsBeforeLastNodeOffset(s.offsetInContainerNode(), s.containerNode()));
                     e = lastPositionInOrAfterNode(prev.get());
                 }
             }
@@ skipping 403 matching lines @@
 void ApplyStyleCommand::trace(Visitor* visitor)
 {
     visitor->trace(m_style);
     visitor->trace(m_start);
     visitor->trace(m_end);
     visitor->trace(m_styledInlineElement);
     CompositeEditCommand::trace(visitor);
 }
 
 }