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

Source/core/layout/LayoutBoxModelObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 436 matching lines @@
 {
     const ComputedStyle& styleToUse = styleRef();
     setHasBoxDecorationBackground(calculateHasBoxDecorations());
     setInline(styleToUse.isDisplayInlineType());
     setPositionState(styleToUse.position());
     setHorizontalWritingMode(styleToUse.isHorizontalWritingMode());
 }
 
 static LayoutSize accumulateInFlowPositionOffsets(const LayoutObject* child)
 {
-    if (!child->isAnonymousBlock() || !child->isRelPositioned())
+    if (!child->isAnonymousBlock() || !child->isInFlowPositioned())
         return LayoutSize();
     LayoutSize offset;
     LayoutObject* p = toLayoutBlock(child)->inlineElementContinuation();
     while (p && p->isLayoutInline()) {
-        if (p->isRelPositioned()) {
+        if (p->isInFlowPositioned()) {
             LayoutInline* layoutInline = toLayoutInline(p);
             offset += layoutInline->offsetForInFlowPosition();
         }
         p = p->parent();
     }
     return offset;
 }
 
 LayoutBlock* LayoutBoxModelObject::containingBlockForAutoHeightDetection(Length logicalHeight) const
 {
@@ skipping 96 matching lines @@
     // return the distance between the canvas origin and the left border edge
     // of the element and stop this algorithm.
     Element* element = offsetParent();
     if (!element)
         return referencePoint;
 
     if (const LayoutBoxModelObject* offsetParent = element->layoutBoxModelObject()) {
         if (offsetParent->isBox() && !offsetParent->isBody())
             referencePoint.move(-toLayoutBox(offsetParent)->borderLeft(), -toLayoutBox(offsetParent)->borderTop());
         if (!isOutOfFlowPositioned() || flowThreadContainingBlock()) {
-            if (isRelPositioned())
+            if (isInFlowPositioned())
                 referencePoint.move(relativePositionOffset());
 
             LayoutObject* current;
             for (current = parent(); current != offsetParent && current->parent(); current = current->parent()) {
                 // FIXME: What are we supposed to do inside SVG content?
                 if (!isOutOfFlowPositioned()) {
                     if (current->isBox() && !current->isTableRow())
                         referencePoint.moveBy(toLayoutBox(current)->topLeftLocation());
                     referencePoint.move(current->parent()->columnOffset(referencePoint));
                 }
@@ skipping 413 matching lines @@
     if (rootElementStyle->hasBackground())
         return false;
 
     if (node() != document().firstBodyElement())
         return false;
 
     return true;
 }
 
 } // namespace blink