Oilpan: fix build after r183913.

Source/core/dom/PseudoElement.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 14 matching lines @@
  */
 
 #ifndef PseudoElement_h
 #define PseudoElement_h
 
 #include "core/dom/Element.h"
 #include "core/rendering/style/RenderStyle.h"
 
 namespace blink {
 
-class RenderTextFragment;
-
 class PseudoElement : public Element {
 public:
     static PassRefPtrWillBeRawPtr<PseudoElement> create(Element* parent, PseudoId);
 
     virtual PassRefPtr<RenderStyle> customStyleForRenderer() override;
     virtual void attach(const AttachContext& = AttachContext()) override;
     virtual bool rendererIsNeeded(const RenderStyle&) override;
 
     virtual bool canStartSelection() const override { return false; }
     virtual bool canContainRangeEndPoint() const override { return false; }
@@ skipping 23 matching lines @@
     if (style->styleType() == FIRST_LETTER || style->styleType() == BACKDROP)
         return true;
     return style->contentData();
 }
 
 DEFINE_ELEMENT_TYPE_CASTS(PseudoElement, isPseudoElement());
 
 } // namespace
 
 #endif