Generate scroll/clip display item hierarchy for SPv2

Source/core/paint/BoxClipper.cpp

Index: Source/core/paint/BoxClipper.cpp
diff --git a/Source/core/paint/BoxClipper.cpp b/Source/core/paint/BoxClipper.cpp
index 488183aa7f4f0d6092beb61505c03257dece97c9..199a79c4c2667e1b43a7562d4820f2a63fdf1f6e 100644
--- a/Source/core/paint/BoxClipper.cpp
+++ b/Source/core/paint/BoxClipper.cpp
@@ -24,7 +24,7 @@ BoxClipper::BoxClipper(const LayoutBox& box, const PaintInfo& paintInfo, const L
         return;
 
     bool isControlClip = m_box.hasControlClip();
-    bool isOverflowClip = m_box.hasOverflowClip() && !m_box.layer()->isSelfPaintingLayer();
+    bool isOverflowClip = m_box.hasOverflowClip() && (!m_box.layer()->isSelfPaintingLayer() || RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
     if (!isControlClip && !isOverflowClip)
         return;
@@ -35,7 +35,7 @@ BoxClipper::BoxClipper(const LayoutBox& box, const PaintInfo& paintInfo, const L
     if (hasBorderRadius)
         clipRoundedRect = m_box.style()->getRoundedInnerBorderFor(LayoutRect(accumulatedOffset, m_box.size()));
 
-    if (contentsClipBehavior == SkipContentsClipIfPossible) {
+    if (contentsClipBehavior == SkipContentsClipIfPossible && !RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
         LayoutRect contentsVisualOverflow = m_box.contentsVisualOverflowRect();
         if (contentsVisualOverflow.isEmpty())
             return;
@@ -74,7 +74,7 @@ BoxClipper::~BoxClipper()
     if (m_clipType == DisplayItem::UninitializedType)
         return;
 
-    ASSERT(m_box.hasControlClip() || (m_box.hasOverflowClip() && !m_box.layer()->isSelfPaintingLayer()));
+    ASSERT(m_box.hasControlClip() || (m_box.hasOverflowClip() && (!m_box.layer()->isSelfPaintingLayer() || RuntimeEnabledFeatures::slimmingPaintV2Enabled())));
 
     if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
         ASSERT(m_paintInfo.context->displayItemList());