WIP for display item list backed by ListContainer

Source/platform/graphics/paint/DisplayItemListTest.cpp

Index: Source/platform/graphics/paint/DisplayItemListTest.cpp
diff --git a/Source/platform/graphics/paint/DisplayItemListTest.cpp b/Source/platform/graphics/paint/DisplayItemListTest.cpp
index ef71fb1d9fd2d9171ef35488e136f555b821a084..e4ff3523cf6b41d921e85cfa9c5737620a3e94e7 100644
--- a/Source/platform/graphics/paint/DisplayItemListTest.cpp
+++ b/Source/platform/graphics/paint/DisplayItemListTest.cpp
@@ -57,7 +57,11 @@ private:
 
 class TestDisplayItem : public DisplayItem {
 public:
-    TestDisplayItem(const DisplayItemClientWrapper& client, Type type) : DisplayItem(client, type) { }
+    TestDisplayItem(TestDisplayItemClient& client, Type type)
+    {
+        DisplayItemClientWrapper clientWrapper(client);
+        setClientAndType(clientWrapper, type);
+    }
 
     virtual void replay(GraphicsContext&) override final { ASSERT_NOT_REACHED(); }
     virtual void appendToWebDisplayItemList(WebDisplayItemList*) const override final { ASSERT_NOT_REACHED(); }