Let collapsed border drawings be cacheable

Source/platform/graphics/paint/DisplayItemTest.cpp

 // Copyright 2015 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"
 
 #include <gtest/gtest.h>
 
 namespace blink {
 namespace {
 
 #ifndef NDEBUG
 TEST(DisplayItemTest, DebugStringsExist)
 {
     for (int type = 0; type <= DisplayItem::TypeLast; type++) {
+        DisplayItem::Type nonCachedType = DisplayItem::nonCachedType(static_cast<DisplayItem::Type>(type));

[pdr., 2015/08/21 00:08:22]

Can we remove the special case for collapsed borders here? I think you can just
adjust specialDrawingTypeAsDebugString to print out
TableCollapsedBorderAlignment.

[Xianzhu, 2015/08/21 17:11:52]

Done.

+        if (nonCachedType >= DisplayItem::TableCollapsedBorderUnalignedBase && nonCachedType <= DisplayItem::TableCollapsedBorderBase)
+            continue;
+
         String debugString = DisplayItem::typeAsDebugString(static_cast<DisplayItem::Type>(type));
         EXPECT_FALSE(debugString.isEmpty());
         EXPECT_NE("Unknown", debugString);
     }
 }
 #endif // NDEBUG
 
 } // namespace
 } // namespace blink