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

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 f60375f6c683c1d4b275c218ae8a1715967072b0..e31b6fd83f7d459b4c7771cb175df483dd246085 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -46,6 +46,7 @@
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderDeprecatedFlexibleBox.h"
 #include "core/rendering/RenderFlexibleBox.h"
+#include "core/rendering/RenderFlowThread.h"
 #include "core/rendering/RenderGeometryMap.h"
 #include "core/rendering/RenderGrid.h"
 #include "core/rendering/RenderInline.h"
@@ -1427,7 +1428,11 @@ LayoutUnit RenderBox::containingBlockLogicalWidthForContent() const
     if (hasOverrideContainingBlockLogicalWidth())
         return overrideContainingBlockContentLogicalWidth();
 
-    RenderBlock* cb = containingBlock();
+    RenderBlock* cb;
+    if (isColumnSpanAll())
+        cb = flowThreadContainingBlock()->containingBlock();
+    else
+        cb = containingBlock();

[Julien - ping for review, 2014/11/17 23:47:11]

Why don't we patch containingBlock to return the right answer for
isColumnSpanAll()? Those 2 containing block changes seems very artificial.

[mstensho (USE GERRIT), 2014/11/18 13:29:26]

Done. A patch for this particular issue is uploaded separately, since it
entailed quite a few changes.

     return cb->availableLogicalWidth();
 }
 
@@ -1436,7 +1441,11 @@ LayoutUnit RenderBox::containingBlockLogicalHeightForContent(AvailableLogicalHei
     if (hasOverrideContainingBlockLogicalHeight())
         return overrideContainingBlockContentLogicalHeight();
 
-    RenderBlock* cb = containingBlock();
+    RenderBlock* cb;
+    if (isColumnSpanAll())
+        cb = flowThreadContainingBlock()->containingBlock();
+    else
+        cb = containingBlock();
     return cb->availableLogicalHeight(heightType);
 }
 
@@ -4121,7 +4130,11 @@ bool RenderBox::hasUnsplittableScrollingOverflow() const
 
 bool RenderBox::isUnsplittableForPagination() const
 {
-    return isReplaced() || hasUnsplittableScrollingOverflow() || (parent() && isWritingModeRoot());
+    // FIXME: column spanners are only unsplittable (or rather: they do not participate in

[Julien - ping for review, 2014/11/17 23:47:11]

It's unclear what action needs to be taken to close this FIXME. We should make
it clear in case it goes stale.

[mstensho (USE GERRIT), 2014/11/18 13:29:26]

Done.

I just removed the column spanner condition for now. None of the tests depend on
it. Maybe I need it later. It would be fine to have the test here (as long as we
don't support nested fragmentation), although it's not exactly correct, as the
comment tried to communicate. :) If I need it later, I'll try to come up with a
better comment.

+    // fragmentation) in their nearest ancestor multicol container. If there are additional
+    // fragmentation contexts further up in the tree, spanners still need to take those into
+    // account.
+    return isReplaced() || hasUnsplittableScrollingOverflow() || (parent() && isWritingModeRoot()) || isColumnSpanAll();
 }
 
 LayoutUnit RenderBox::lineHeight(bool /*firstLine*/, LineDirectionMode direction, LinePositionMode /*linePositionMode*/) const