Generate scroll/clip display item hierarchy for SPv2

Source/platform/graphics/paint/DisplayItem.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "platform/graphics/paint/DisplayItem.h"
 
 namespace blink {
 
 struct SameSizeAsDisplayItem {
@@ skipping 110 matching lines @@
     return "Drawing" + specialDrawingTypeAsDebugString(type);
 }
 
 static WTF::String clipTypeAsDebugString(DisplayItem::Type type)
 {
     PAINT_PHASE_BASED_DEBUG_STRINGS(ClipBox);
     PAINT_PHASE_BASED_DEBUG_STRINGS(ClipColumnBounds);
     PAINT_PHASE_BASED_DEBUG_STRINGS(ClipLayerFragment);
 
     switch (type) {
+        DEBUG_STRING_CASE(ClipDescendantStackingContext);
         DEBUG_STRING_CASE(ClipFileUploadControlRect);
         DEBUG_STRING_CASE(ClipFrameToVisibleContentRect);
         DEBUG_STRING_CASE(ClipFrameScrollbars);
         DEBUG_STRING_CASE(ClipLayerBackground);
         DEBUG_STRING_CASE(ClipLayerColumnBounds);
         DEBUG_STRING_CASE(ClipLayerFilter);
         DEBUG_STRING_CASE(ClipLayerForeground);
         DEBUG_STRING_CASE(ClipLayerParent);
         DEBUG_STRING_CASE(ClipLayerOverflowControls);
         DEBUG_STRING_CASE(ClipNodeImage);
@@ skipping 89 matching lines @@
     stringBuilder.append('"');
     if (m_skippedCache)
         stringBuilder.append(", skippedCache: true");
     if (m_scope)
         stringBuilder.append(String::format(", scope: %d", m_scope));
 }
 
 #endif
 
 } // namespace blink