It's not just the last column set that may need additional fragmentainer groups.

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 5f114cf6b8f25bff7b0b037495ef027cfda03d09..b316cf8f4c96eb78251cd144fb91ddd1e9d1266e 100644
--- a/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutMultiColumnSet.cpp
@@ -146,6 +146,14 @@ LayoutMultiColumnSet* LayoutMultiColumnSet::previousSiblingMultiColumnSet() cons
     return nullptr;
 }
 
+bool LayoutMultiColumnSet::hasFragmentainerGroupForColumnAt(LayoutUnit offsetInFlowThread) const
+{
+    const MultiColumnFragmentainerGroup& lastRow = lastFragmentainerGroup();
+    if (lastRow.logicalTopInFlowThread() > offsetInFlowThread)
+        return true;
+    return offsetInFlowThread - lastRow.logicalTopInFlowThread() < lastRow.logicalHeight() * usedColumnCount();
+}
+
 MultiColumnFragmentainerGroup& LayoutMultiColumnSet::appendNewFragmentainerGroup()
 {
     MultiColumnFragmentainerGroup newGroup(*this);