Implement Paint Containment

third_party/WebKit/Source/core/paint/BoxClipper.cpp

Index: third_party/WebKit/Source/core/paint/BoxClipper.cpp
diff --git a/third_party/WebKit/Source/core/paint/BoxClipper.cpp b/third_party/WebKit/Source/core/paint/BoxClipper.cpp
index ac13973d42cbddb149dc5be30516f9bd4cb7ab7a..09f10cff24cc885149050968cb75e938352917ce 100644
--- a/third_party/WebKit/Source/core/paint/BoxClipper.cpp
+++ b/third_party/WebKit/Source/core/paint/BoxClipper.cpp
@@ -24,9 +24,10 @@ 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 isOverflowOrContainmentClip = (m_box.hasOverflowClip() && !m_box.layer()->isSelfPaintingLayer())
+        || m_box.style()->containsPaint();
 
-    if (!isControlClip && !isOverflowClip)
+    if (!isControlClip && !isOverflowOrContainmentClip)
         return;
 
     LayoutRect clipRect = isControlClip ? m_box.controlClipRect(accumulatedOffset) : m_box.overflowClipRect(accumulatedOffset);
@@ -64,7 +65,7 @@ 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()) || m_box.style()->containsPaint());
     m_paintInfo.context.paintController().endItem<EndClipDisplayItem>(m_box, DisplayItem::clipTypeToEndClipType(m_clipType));
 }