[Layout API] Use Document::layoutViewItem in WebFrameTest

third_party/WebKit/Source/core/layout/api/LayoutItem.h

 // Copyright 2016 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 LayoutItem_h
 #define LayoutItem_h
 
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/layout/LayoutObject.h"
 
@@ skipping 159 matching lines @@
     void updateStyleAndLayout()
     {
         return m_layoutObject->document().updateStyleAndLayout();
     }
 
     const ComputedStyle& styleRef() const
     {
         return m_layoutObject->styleRef();
     }
 
+    ComputedStyle& mutableStyleRef() const
+    {
+        return m_layoutObject->mutableStyleRef();
+    }
+
     LayoutSize offsetFromContainer(const LayoutItem& item) const
     {
         return m_layoutObject->offsetFromContainer(item.layoutObject());
     }
 
     FrameView* frameView() const
     {
         return m_layoutObject->document().view();
     }
 
@@ skipping 78 matching lines @@
 
 private:
     LayoutObject* m_layoutObject;
 
     friend class LayoutAPIShim;
 };
 
 } // namespace blink
 
 #endif // LayoutItem_h