Reland main thread position sticky implementation.

third_party/WebKit/Source/core/layout/LayoutBlockFlow.cpp

 /*
  * Copyright (C) 2013 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 312 matching lines @@
     LayoutUnit pageLogicalHeight;
     while (!done)
         done = layoutBlockFlow(relayoutChildren, pageLogicalHeight, layoutScope);
 
     LayoutView* layoutView = view();
     if (layoutView->layoutState()->pageLogicalHeight())
         setPageLogicalOffset(layoutView->layoutState()->pageLogicalOffset(*this, logicalTop()));
 
     updateLayerTransformAfterLayout();
 
-    // Update our scroll information if we're overflow:auto/scroll/hidden now that we know if
-    // we overflow or not.
-    updateScrollInfoAfterLayout();
+    updateAfterLayout();
 
     if (m_paintInvalidationLogicalTop != m_paintInvalidationLogicalBottom) {
         bool hasVisibleContent = style()->visibility() == VISIBLE;
         if (!hasVisibleContent) {
             PaintLayer* layer = enclosingLayer();
             layer->updateDescendantDependentFlags();
             hasVisibleContent = layer->hasVisibleContent();
         }
         if (hasVisibleContent)
             setShouldInvalidateOverflowForPaint();
@@ skipping 2686 matching lines @@
     // FIXME: Glyph overflow will get lost in this case, but not really a big deal.
     GlyphOverflowAndFallbackFontsMap textBoxDataMap;
     for (ListHashSet<RootInlineBox*>::const_iterator it = lineBoxes.begin(); it != lineBoxes.end(); ++it) {
         RootInlineBox* box = *it;
         box->computeOverflow(box->lineTop(), box->lineBottom(), textBoxDataMap);
     }
     return childrenOverflowChanged;
 }
 
 } // namespace blink