Don't cache subsequence whose layer is not fully contained by repaint rect

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 212 matching lines @@
     stringBuilder.append(String::format("client: \"%p", client()));
     if (!clientDebugString().isEmpty()) {
         stringBuilder.append(' ');
         stringBuilder.append(clientDebugString());
     }
     stringBuilder.append("\", type: \"");
     stringBuilder.append(typeAsDebugString(type()));
     stringBuilder.append('"');
     if (m_skippedCache)
         stringBuilder.append(", skippedCache: true");
+    if (m_isUncacheable)
+        stringBuilder.append(", isUncacheable: true");
     if (m_scope)
         stringBuilder.append(String::format(", scope: %d", m_scope));
 }
 
 #endif
 
 } // namespace blink