All ancestor multicols must have enough rows before laying out some inner multicol.

third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp

Index: third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp b/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
index 95802c07dd177b1cfd07f9e1268db0ac178e2a4f..bedf6229414e0fefe4e05796c48e08fcb5a3f7f8 100644
--- a/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
@@ -178,12 +178,13 @@ LayoutMultiColumnSet* LayoutMultiColumnSet::previousSiblingMultiColumnSet() cons
     return nullptr;
 }
 
-bool LayoutMultiColumnSet::hasFragmentainerGroupForColumnAt(LayoutUnit bottomOffsetInFlowThread) const
+bool LayoutMultiColumnSet::hasFragmentainerGroupForColumnAt(LayoutUnit offsetInFlowThread, PageBoundaryRule pageBoundaryRule) const
 {
     const MultiColumnFragmentainerGroup& lastRow = lastFragmentainerGroup();
-    if (lastRow.logicalTopInFlowThread() > bottomOffsetInFlowThread)
-        return true;
-    return bottomOffsetInFlowThread - lastRow.logicalTopInFlowThread() <= lastRow.logicalHeight() * usedColumnCount();
+    LayoutUnit maxLogicalBottomInFlowThread = lastRow.logicalTopInFlowThread() + lastRow.logicalHeight() * usedColumnCount();
+    if (pageBoundaryRule == AssociateWithFormerPage)
+        return offsetInFlowThread <= maxLogicalBottomInFlowThread;
+    return offsetInFlowThread < maxLogicalBottomInFlowThread;
 }
 
 MultiColumnFragmentainerGroup& LayoutMultiColumnSet::appendNewFragmentainerGroup()