[SPv2] Add CSS mask support

third_party/WebKit/Source/core/layout/LayoutTestHelper.h

 // 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.
 
 #ifndef LayoutTestHelper_h
 #define LayoutTestHelper_h
 
 #include "core/dom/Document.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
@@ skipping 94 matching lines @@
     document().view()->setParentVisible(true);
     document().view()->setSelfVisible(true);
     document().view()->updateAllLifecyclePhases();
   }
 
   LayoutObject* getLayoutObjectByElementId(const char* id) const {
     Node* node = document().getElementById(id);
     return node ? node->layoutObject() : nullptr;
   }
 
+  void loadAhem();
+
  private:
   Persistent<FrameLoaderClient> m_frameLoaderClient;
   std::unique_ptr<DummyPageHolder> m_pageHolder;
 };
 
 }  // namespace blink
 
 #endif  // LayoutTestHelper_h