Fix assertion failure during out-of-order matching

Source/platform/graphics/paint/DisplayItemListTest.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/DisplayItemList.h"
 
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/paint/CachedDisplayItem.h"
@@ skipping 498 matching lines @@
         TestDisplayItem(container2, DisplayItem::EndSubsequence),
 
         TestDisplayItem(container1, DisplayItem::BeginSubsequence),
         TestDisplayItem(container1, backgroundDrawingType),
         TestDisplayItem(content1, backgroundDrawingType),
         TestDisplayItem(content1, foregroundDrawingType),
         TestDisplayItem(container1, foregroundDrawingType),
         TestDisplayItem(container1, DisplayItem::EndSubsequence));
 }
 
+TEST_F(DisplayItemListTest, OutOfOrderNoCrash)
+{
+    TestDisplayItemClient client("client");
+    GraphicsContext context(&displayItemList());
+
+    const DisplayItem::Type type1 = DisplayItem::DrawingFirst;
+    const DisplayItem::Type type2 = static_cast<DisplayItem::Type>(DisplayItem::DrawingFirst + 1);
+    const DisplayItem::Type type3 = static_cast<DisplayItem::Type>(DisplayItem::DrawingFirst + 2);
+    const DisplayItem::Type type4 = static_cast<DisplayItem::Type>(DisplayItem::DrawingFirst + 3);
+
+    drawRect(context, client, type1, FloatRect(100, 100, 100, 100));
+    drawRect(context, client, type2, FloatRect(100, 100, 50, 200));
+    drawRect(context, client, type3, FloatRect(100, 100, 50, 200));
+    drawRect(context, client, type4, FloatRect(100, 100, 100, 100));
+
+    displayItemList().commitNewDisplayItems();
+
+    drawRect(context, client, type2, FloatRect(100, 100, 50, 200));
+    drawRect(context, client, type3, FloatRect(100, 100, 50, 200));
+    drawRect(context, client, type1, FloatRect(100, 100, 100, 100));
+    drawRect(context, client, type4, FloatRect(100, 100, 100, 100));
+
+    displayItemList().commitNewDisplayItems();
+}
+
 TEST_F(DisplayItemListTest, CachedNestedSubsequenceUpdate)
 {
     TestDisplayItemClient container1("container1");
     TestDisplayItemClient content1("content1");
     TestDisplayItemClient container2("container2");
     TestDisplayItemClient content2("content2");
     GraphicsContext context(&displayItemList());
 
     {
         SubsequenceRecorder r(context, container1);
@@ skipping 211 matching lines @@
     drawRect(context, third, backgroundDrawingType, FloatRect(0, 0, 100, 100));
     displayItemList().commitNewDisplayItems();
 
     // Empty clips should have been optimized out.
     EXPECT_DISPLAY_LIST(displayItemList().displayItems(), 2,
         TestDisplayItem(first, backgroundDrawingType),
         TestDisplayItem(third, backgroundDrawingType));
 }
 
 } // namespace blink