*** DO NOT LAND *** Implement column-span:all without reparenting renderers. Work in progress.

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index 96d8174c1fb0bd499123ce3b368f811f14d92b4e..45ec1607f3e0251c2ecaee8e2d797ecbddd7530c 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -225,6 +225,11 @@ void RenderBox::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle
 
     updateShapeOutsideInfoAfterStyleChange(*style(), oldStyle);
     updateGridPositionAfterStyleChange(oldStyle);
+
+    if (RenderFlowThread* flowThread = flowThreadContainingBlock()) {
+        if (flowThread != this)
+            flowThread->flowThreadDescendantStyleDidChange(this);
+    }
 }
 
 void RenderBox::updateShapeOutsideInfoAfterStyleChange(const RenderStyle& style, const RenderStyle* oldStyle)
@@ -2345,7 +2350,7 @@ bool RenderBox::autoWidthShouldFitContent() const
 void RenderBox::computeMarginsForDirection(MarginDirection flowDirection, const RenderBlock* containingBlock, LayoutUnit containerWidth, LayoutUnit childWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd, Length marginStartLength, Length marginEndLength) const
 {
     if (flowDirection == BlockDirection || isFloating() || isInline()) {
-        if (isTableCell() && flowDirection == BlockDirection) {
+        if ((isColumnSpanAll() || isTableCell()) && flowDirection == BlockDirection) {
             // FIXME: Not right if we allow cells to have different directionality than the table. If we do allow this, though,
             // we may just do it with an extra anonymous block inside the cell.
             marginStart = 0;
@@ -4470,14 +4475,8 @@ LayoutRect RenderBox::layoutOverflowRectForPropagation(RenderStyle* parentStyle)
     LayoutRect rect = borderBoxRect();
     // We want to include the margin, but only when it adds height. Quirky margins don't contribute height
     // nor do the margins of self-collapsing blocks.
-    if (!style()->hasMarginAfterQuirk() && !isSelfCollapsingBlock()) {
-        LayoutState* layoutState = view()->layoutState();
-        // FIXME: if the margin has collapsed with a page/column boundary, the part that got
-        // collapsed away must not be propagated here. All other margins should be propagated,
-        // though, but for now, we just ignore them in paginated mode.
-        if (!layoutState || !layoutState->isPaginated())
-            rect.expand(isHorizontalWritingMode() ? LayoutSize(LayoutUnit(), marginAfter()) : LayoutSize(marginAfter(), LayoutUnit()));
-    }
+    if (!style()->hasMarginAfterQuirk() && !isSelfCollapsingBlock())
+        rect.expand(isHorizontalWritingMode() ? LayoutSize(LayoutUnit(), marginAfter()) : LayoutSize(marginAfter(), LayoutUnit()));
 
     if (!hasOverflowClip())
         rect.unite(layoutOverflowRect());