Disable layout optimization when column height may be non-uniform.

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

Index: third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp b/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
index 807fe9613ec144b1f4f625462cc71d5cc13c50a5..f532eda6c4fe53b75066dad7cc7e9ea11f635e7b 100644
--- a/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
@@ -365,6 +365,15 @@ bool LayoutMultiColumnFlowThread::isPageLogicalHeightKnown() const {
   return false;
 }
 
+bool LayoutMultiColumnFlowThread::mayHaveNonUniformPageLogicalHeight() const {
+  const LayoutMultiColumnSet* columnSet = firstMultiColumnSet();
+  if (!columnSet)
+    return false;
+  if (columnSet->nextSiblingMultiColumnSet())
+    return true;
+  return enclosingFragmentationContext();
+}
+
 LayoutSize LayoutMultiColumnFlowThread::flowThreadTranslationAtOffset(
     LayoutUnit offsetInFlowThread,
     PageBoundaryRule rule,