Slimming Paint phase 2 compositing algorithm plumbing

Source/platform/graphics/ContentLayerDelegate.cpp

Index: Source/platform/graphics/ContentLayerDelegate.cpp
diff --git a/Source/platform/graphics/ContentLayerDelegate.cpp b/Source/platform/graphics/ContentLayerDelegate.cpp
index 657ecb92854104a0c810de448a4d56e21085ef67..90019a04cf3169e839c1a0de081845d0e3b467c1 100644
--- a/Source/platform/graphics/ContentLayerDelegate.cpp
+++ b/Source/platform/graphics/ContentLayerDelegate.cpp
@@ -90,6 +90,17 @@ void ContentLayerDelegate::paintContents(
 
     ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());
 
+    // TODO(pdr): Remove when slimming paint v2 is further along. This is only
+    // here so the browser is usable during development and does not crash due
+    // to committing the new display items twice.
+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
+        if (m_painter->displayItemList()) {
+            for (auto& displayItem : m_painter->displayItemList()->displayItems())
+                displayItem.appendToWebDisplayItemList(webDisplayItemList);
+        }
+        return;
+    }
+
     DisplayItemList* displayItemList = m_painter->displayItemList();
     ASSERT(displayItemList);
     displayItemList->setDisplayItemConstructionIsDisabled(