Allow passing mock FrameLoaderClient to DummyPageHolder.

Source/core/page/PrintContextTest.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 "core/page/PrintContext.h"
 
 #include "core/dom/Document.h"
+#include "core/html/HTMLElement.h"
 #include "core/testing/DummyPageHolder.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/testing/SkiaForCoreTesting.h"
 #include "platform/text/TextStream.h"
 #include <gtest/gtest.h>
 
 namespace blink {
 
 const int kPageWidth = 800;
 const int kPageHeight = 600;
@@ skipping 130 matching lines @@
     size_t firstIndex = operations[0].rect.x() == 50 ? 0 : 1;
     EXPECT_EQ(MockCanvas::DrawRect, operations[firstIndex].type);
     EXPECT_SKRECT_EQ(50, 60, 70, 80, operations[firstIndex].rect);
 
     size_t secondIndex = firstIndex == 0 ? 1 : 0;
     EXPECT_EQ(MockCanvas::DrawPoint, operations[secondIndex].type);
     EXPECT_SKRECT_EQ(250, 260, 0, 0, operations[secondIndex].rect);
 }
 
 } // namespace blink