Support display: contents for elements, first-line and first-letter pseudos.

third_party/WebKit/Source/core/dom/LayoutTreeBuilderTraversal.h

 /*
  * Copyright (C) 2012 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.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 43 matching lines @@
     return m_insertionPoint == other.m_insertionPoint;
   }
 
  private:
   Member<const InsertionPoint> m_insertionPoint;
 };
 
 CORE_EXPORT ContainerNode* parent(const Node&, ParentDetails* = 0);
 CORE_EXPORT Node* firstChild(const Node&);
 CORE_EXPORT Node* nextSibling(const Node&);
+LayoutObject* parentLayoutObject(const Node&);

[rune, 2016/11/01 07:12:23]

This is just one of the changes you need in LayoutTreeBuilderTraversal. Can I
suggest that you start out with a CL implementing necessary changes in
LayoutTreeBuilderTraversal and write unit tests for it?

[emilio, 2016/11/01 15:46:31]

I agree. I've pushed a new version of the changeset doing more modifications to
find{Next,Previous}SiblingLayoutObject, recursing into display: contents nodes,
and looking up if our parent is a display: contents node and we don't find a
sibling. Hopefully that looks more like what you were expecting. I also added a
test responding to dynamic changes, since I didn't know how to unit-test the
traversal. If you give me some pointers, I'm happy to add extensive unit tests
for a bunch of edge cases. I'll try to write them in terms of reftests
otherwise.

I can try to split that off the rest of this CL, if you think that's
appropriate, though I don't think it'll become much smaller than this. 

 Node* previousSibling(const Node&);
 Node* previous(const Node&, const Node* stayWithin);
 Node* next(const Node&, const Node* stayWithin);
 Node* nextSkippingChildren(const Node&, const Node* stayWithin);
 LayoutObject* nextSiblingLayoutObject(const Node&,
                                       int32_t limit = kTraverseAllSiblings);
 LayoutObject* previousSiblingLayoutObject(const Node&,
                                           int32_t limit = kTraverseAllSiblings);
 LayoutObject* nextInTopLayer(const Element&);
 
 inline Element* parentElement(const Node& node) {
   ContainerNode* found = parent(node);
   return found && found->isElementNode() ? toElement(found) : 0;
 }
 
 }  // namespace LayoutTreeBuilderTraversal
 
 }  // namespace blink
 
 #endif