[New Multicolumn] Actual support for layout of column-span:all.

Source/core/rendering/RenderBlockFlow.cpp

Index: Source/core/rendering/RenderBlockFlow.cpp
diff --git a/Source/core/rendering/RenderBlockFlow.cpp b/Source/core/rendering/RenderBlockFlow.cpp
index afc0212fa770522ad2b8b05610560df1286d5192..6e7ddee59d2e1678777ac80e797ca5ec20b93093 100644
--- a/Source/core/rendering/RenderBlockFlow.cpp
+++ b/Source/core/rendering/RenderBlockFlow.cpp
@@ -546,11 +546,46 @@ void RenderBlockFlow::setLogicalTopForChild(RenderBox* child, LayoutUnit logical
     }
 }
 
+class ColumnSpannerLayoutScope {
+public:
+    ColumnSpannerLayoutScope()
+        : m_spanner(0)
+    {
+    }
+
+    ~ColumnSpannerLayoutScope()
+    {
+        if (!m_spanner)
+            return;
+        m_spanner->flowThreadContainingBlock()->exitColumnSpannerAfterLayout(m_spanner, m_spanner->parentBlock()->logicalHeight());
+    }
+
+    LayoutUnit enterSpanner(RenderBox* spanner, SubtreeLayoutScope& layoutScope)
+    {
+        ASSERT(!m_spanner);
+        m_spanner = spanner;
+        return m_spanner->flowThreadContainingBlock()->enterColumnSpannerBeforeLayout(m_spanner, m_spanner->parentBlock()->logicalHeight(), layoutScope);
+    }
+
+private:
+    RenderBox* m_spanner;
+};
+
 void RenderBlockFlow::layoutBlockChild(RenderBox* child, MarginInfo& marginInfo, LayoutUnit& previousFloatLogicalBottom)
 {
     LayoutUnit oldPosMarginBefore = maxPositiveMarginBefore();
     LayoutUnit oldNegMarginBefore = maxNegativeMarginBefore();
 
+    SubtreeLayoutScope layoutScope(*child);
+
+    ColumnSpannerLayoutScope columnSpannerLayoutScope;
+    if (child->isColumnSpanAll()) {
+        LayoutUnit adjustment = columnSpannerLayoutScope.enterSpanner(child, layoutScope);
+        // A spanner needs to start at an exact column boundary inside the flow thread, so that it
+        // doesn't bleed into a preceding column. That's what the adjustment is about.
+        setLogicalHeight(logicalHeight() + adjustment);
+    }
+
     // The child is a normal flow object. Compute the margins we will use for collapsing now.
     child->computeAndSetBlockDirectionMargins(this);
 
@@ -592,7 +627,6 @@ void RenderBlockFlow::layoutBlockChild(RenderBox* child, MarginInfo& marginInfo,
             previousFloatLogicalBottom = std::max(previousFloatLogicalBottom, oldLogicalTop + childRenderBlockFlow->lowestFloatLogicalBottom());
     }
 
-    SubtreeLayoutScope layoutScope(*child);
     if (!child->needsLayout())
         child->markForPaginationRelayoutIfNeeded(layoutScope);
 
@@ -867,6 +901,8 @@ void RenderBlockFlow::adjustLinePositionForPagination(RootInlineBox* lineBox, La
 
 LayoutUnit RenderBlockFlow::adjustForUnsplittableChild(RenderBox* child, LayoutUnit logicalOffset, bool includeMargins)
 {
+    if (child->isColumnSpanAll())
+        return logicalOffset;
     bool checkColumnBreaks = view()->layoutState()->isPaginatingColumns() || flowThreadContainingBlock();
     bool checkPageBreaks = !checkColumnBreaks && view()->layoutState()->pageLogicalHeight();
     bool isUnsplittable = child->isUnsplittableForPagination() || (checkColumnBreaks && child->style()->columnBreakInside() == PBAVOID)
@@ -1297,7 +1333,7 @@ LayoutUnit RenderBlockFlow::collapseMargins(RenderBox* child, MarginInfo& margin
     // If margins would pull us past the top of the next page, then we need to pull back and pretend like the margins
     // collapsed into the page edge.
     LayoutState* layoutState = view()->layoutState();
-    if (layoutState->isPaginated() && layoutState->pageLogicalHeight() && logicalTop > beforeCollapseLogicalTop) {
+    if (layoutState->isPaginated() && layoutState->pageLogicalHeight() && logicalTop > beforeCollapseLogicalTop && !child->isColumnSpanAll()) {
         LayoutUnit oldLogicalTop = logicalTop;
         logicalTop = std::min(logicalTop, nextPageLogicalTop(beforeCollapseLogicalTop));
         setLogicalHeight(logicalHeight() + (logicalTop - oldLogicalTop));
@@ -1513,7 +1549,7 @@ LayoutUnit RenderBlockFlow::estimateLogicalTopPosition(RenderBox* child, const M
     // Adjust logicalTopEstimate down to the next page if the margins are so large that we don't fit on the current
     // page.
     LayoutState* layoutState = view()->layoutState();
-    if (layoutState->isPaginated() && layoutState->pageLogicalHeight() && logicalTopEstimate > logicalHeight())
+    if (layoutState->isPaginated() && layoutState->pageLogicalHeight() && logicalTopEstimate > logicalHeight() && !child->isColumnSpanAll())
         logicalTopEstimate = std::min(logicalTopEstimate, nextPageLogicalTop(logicalHeight()));
 
     logicalTopEstimate += getClearDelta(child, logicalTopEstimate);