Need to roll back the multicol machinery state when re-laying out a block child.

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 2e8ca57a591a95df1f963bc7ce406af49dc25d08..f5ffc24d23a67de54242fc8159fadfca3ca86669 100644
--- a/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutMultiColumnFlowThread.cpp
@@ -1047,4 +1047,14 @@ bool LayoutMultiColumnFlowThread::canSkipLayout(const LayoutBox& root) const
     return true;
 }
 
+MultiColumnLayoutState LayoutMultiColumnFlowThread::multiColumnLayoutState() const
+{
+    return MultiColumnLayoutState(m_lastSetWorkedOn);
+}
+
+void LayoutMultiColumnFlowThread::restoreMultiColumnLayoutState(const MultiColumnLayoutState& state)
+{
+    m_lastSetWorkedOn = state.columnSet();
+}
+
 } // namespace blink