Changing out-of-flow-ness on a multicol child may affect the need for column sets.

Source/core/layout/LayoutObject.cpp

Index: Source/core/layout/LayoutObject.cpp
diff --git a/Source/core/layout/LayoutObject.cpp b/Source/core/layout/LayoutObject.cpp
index ea3e8a38731fcb5579ab27e653bd98016a5963d9..72a589fbcc157b0f6ec810731cc6157286d718e9 100644
--- a/Source/core/layout/LayoutObject.cpp
+++ b/Source/core/layout/LayoutObject.cpp
@@ -1754,6 +1754,10 @@ void LayoutObject::setStyle(PassRefPtr<ComputedStyle> style)
 
     diff = adjustStyleDifference(diff);
 
+    if (m_style) {
+        if (LayoutFlowThread* flowThread = flowThreadContainingBlock())
+            flowThread->flowThreadDescendantStyleWillChange(this, diff, *style);
+    }
     styleWillChange(diff, *style);
 
     RefPtr<ComputedStyle> oldStyle = m_style.release();
@@ -1770,6 +1774,10 @@ void LayoutObject::setStyle(PassRefPtr<ComputedStyle> style)
     bool doesNotNeedLayoutOrPaintInvalidation = !m_parent;
 
     styleDidChange(diff, oldStyle.get());
+    if (oldStyle.get()) {
+        if (LayoutFlowThread* flowThread = flowThreadContainingBlock())
+            flowThread->flowThreadDescendantStyleDidChange(this, diff, *oldStyle.get());
+    }
 
     // FIXME: |this| might be destroyed here. This can currently happen for a LayoutTextFragment when
     // its first-letter block gets an update in LayoutTextFragment::styleDidChange. For LayoutTextFragment(s),