[New Multicolumn] Add support for column-span:all

Source/core/rendering/LayoutState.cpp

Index: Source/core/rendering/LayoutState.cpp
diff --git a/Source/core/rendering/LayoutState.cpp b/Source/core/rendering/LayoutState.cpp
index 5a2ba588c863af8ff9a30ec37a578a713a38d08b..8491c891ee4eba35e3b620f3324a8a02066b0e3f 100644
--- a/Source/core/rendering/LayoutState.cpp
+++ b/Source/core/rendering/LayoutState.cpp
@@ -26,6 +26,7 @@
 #include "config.h"
 #include "core/rendering/LayoutState.h"
 
+#include "core/rendering/RenderFlowThread.h"
 #include "core/rendering/RenderInline.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderView.h"
@@ -88,8 +89,14 @@ LayoutState::LayoutState(RenderBox& renderer, const LayoutSize& offset, LayoutUn
         if (renderer.isUnsplittableForPagination()) {
             m_pageLogicalHeight = 0;
             m_isPaginated = false;
+        } else if (RenderFlowThread* flowThread = renderer.flowThreadContainingBlock()) {
+            // FIXME: this won't do if/when we add support for nested fragmentation contexts (e.g. a
+            // multicol container inside something paginated). Note, though, that nested
+            // fragmentation is something that has never worked in the engine (not in the old
+            // multicol implementation either).
+            m_isPaginated = !flowThread->isInsideColumnSpanner(&renderer);
         } else {
-            m_isPaginated = m_pageLogicalHeight || m_next->m_columnInfo || renderer.flowThreadContainingBlock();
+            m_isPaginated = m_pageLogicalHeight || m_next->m_columnInfo;
         }
     }