Add position: sticky as supported position value when CSSStickyPosition is enabled.

Source/core/layout/LayoutObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1075 matching lines @@
     StringBuilder name;
     name.append(this->name());
 
     if (isAnonymous())
         name.append(" (anonymous)");
     // FIXME: Remove the special case for LayoutView here (requires rebaseline of all tests).
     if (isOutOfFlowPositioned() && !isLayoutView())
         name.append(" (positioned)");
     if (isRelPositioned())
         name.append(" (relative positioned)");
+    if (isStickyPositioned())
+        name.append(" (sticky positioned)");
     if (isFloating())
         name.append(" (floating)");
     if (spannerPlaceholder())
         name.append(" (column spanner)");
 
     return name.toString();
 }
 
 String LayoutObject::debugName() const
 {
@@ skipping 890 matching lines @@
         if (blockChildrenOnly && !child->isLayoutBlock())
             continue;
 
         if (child->isLayoutFullScreen() || child->isLayoutFullScreenPlaceholder())
             continue;
 
         RefPtr<ComputedStyle> newStyle = ComputedStyle::createAnonymousStyleWithDisplay(styleRef(), child->style()->display());
 
         // Preserve the position style of anonymous block continuations as they can have relative position when
         // they contain block descendants of relative positioned inlines.
-        if (child->isRelPositioned() && toLayoutBlock(child)->isAnonymousBlockContinuation())
+        if (child->isInFlowPositioned() && toLayoutBlock(child)->isAnonymousBlockContinuation())
             newStyle->setPosition(child->style()->position());
 
         updateAnonymousChildStyle(*child, *newStyle);
 
         child->setStyle(newStyle.release());
     }
 }
 
 void LayoutObject::updateFillImages(const FillLayer* oldLayers, const FillLayer& newLayers)
 {
@@ skipping 1284 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         fprintf(stderr, "Cannot showLayoutTree. Root is (nil)\n");
     }
 }
 
 #endif