Reland main thread position sticky implementation.

third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 178 matching lines @@
     // object wedged in between them. Auto z-index also becomes 0 for objects that specify transforms/masks/reflections.
     if (style.hasAutoZIndex() && ((element && element->document().documentElement() == element)
         || style.hasOpacity()
         || style.hasTransformRelatedProperty()
         || style.hasMask()
         || style.clipPath()
         || style.boxReflect()
         || style.hasFilterInducingProperty()
         || style.hasBlendMode()
         || style.hasIsolation()
-        || style.position() == FixedPosition
+        || style.hasViewportConstrainedPosition()
         || isInTopLayer(element, style)
         || hasWillChangeThatCreatesStackingContext(style)
         || style.containsPaint()))
         style.setZIndex(0);
 
     if (doesNotInheritTextDecoration(style, element))
         style.clearAppliedTextDecorations();
 
     style.applyTextDecorations();
 
@@ skipping 219 matching lines @@
         style.setDisplay(INLINE_BLOCK);
 
     // After performing the display mutation, check table rows. We do not honor position: relative table rows or cells.
     // This has been established for position: relative in CSS2.1 (and caused a crash in containingBlock()
     // on some sites).
     if ((style.display() == TABLE_HEADER_GROUP || style.display() == TABLE_ROW_GROUP
         || style.display() == TABLE_FOOTER_GROUP || style.display() == TABLE_ROW)
         && style.position() == RelativePosition)
         style.setPosition(StaticPosition);
 
+    // Cannot support position: sticky for table columns and column groups because current code is only doing
+    // background painting through columns / column groups
+    if ((style.display() == TABLE_COLUMN_GROUP || style.display() == TABLE_COLUMN)
+        && style.position() == StickyPosition)
+        style.setPosition(StaticPosition);
+
     // writing-mode does not apply to table row groups, table column groups, table rows, and table columns.
     // FIXME: Table cells should be allowed to be perpendicular or flipped with respect to the table, though.
     if (style.display() == TABLE_COLUMN || style.display() == TABLE_COLUMN_GROUP || style.display() == TABLE_FOOTER_GROUP
         || style.display() == TABLE_HEADER_GROUP || style.display() == TABLE_ROW || style.display() == TABLE_ROW_GROUP
         || style.display() == TABLE_CELL)
         style.setWritingMode(parentStyle.getWritingMode());
 
     // FIXME: Since we don't support block-flow on flexible boxes yet, disallow setting
     // of block-flow to anything other than TopToBottomWritingMode.
     // https://bugs.webkit.org/show_bug.cgi?id=46418 - Flexible box support.
     if (style.getWritingMode() != TopToBottomWritingMode && (style.display() == BOX || style.display() == INLINE_BOX))
         style.setWritingMode(TopToBottomWritingMode);
 
     if (parentStyle.isDisplayFlexibleOrGridBox()) {
         style.setFloating(NoFloat);
         style.setDisplay(equivalentBlockDisplay(style.display()));
 
         // We want to count vertical percentage paddings/margins on flex items because our current
         // behavior is different from the spec and we want to gather compatibility data.
         if (style.paddingBefore().hasPercent() || style.paddingAfter().hasPercent())
             UseCounter::count(document, UseCounter::FlexboxPercentagePaddingVertical);
         if (style.marginBefore().hasPercent() || style.marginAfter().hasPercent())
             UseCounter::count(document, UseCounter::FlexboxPercentageMarginVertical);
     }
 }
 
 } // namespace blink