Remove useless null checks from Node::document() call sites

Source/core/svg/SVGElementRareData.h

 /*
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 72 matching lines @@
     }
 
     void destroyAnimatedSMILStyleProperties()
     {
         m_animatedSMILStyleProperties.clear();
     }
 
     RenderStyle* overrideComputedStyle(Element* element, RenderStyle* parentStyle)
     {
         ASSERT(element);
-        if (!element->document() || !m_useOverrideComputedStyle)
+        if (!m_useOverrideComputedStyle)
             return 0;
         if (!m_overrideComputedStyle || m_needsOverrideComputedStyleUpdate) {
             // The style computed here contains no CSS Animations/Transitions or SMIL induced rules - this is needed to compute the "base value" for the SMIL animation sandwhich model.
             m_overrideComputedStyle = element->document()->styleResolver()->styleForElement(element, parentStyle, DisallowStyleSharing, MatchAllRulesExcludingSMIL);
             m_needsOverrideComputedStyleUpdate = false;
         }
         ASSERT(m_overrideComputedStyle);
         return m_overrideComputedStyle.get();
     }
 
     bool useOverrideComputedStyle() const { return m_useOverrideComputedStyle; }
     void setUseOverrideComputedStyle(bool value) { m_useOverrideComputedStyle = value; }
     void setNeedsOverrideComputedStyleUpdate() { m_needsOverrideComputedStyleUpdate = true; }
 
 private:
     HashSet<SVGElementInstance*> m_elementInstances;
     SVGCursorElement* m_cursorElement;
     CSSCursorImageValue* m_cursorImageValue;
     SVGElement* m_correspondingElement;
     bool m_instancesUpdatesBlocked : 1;
     bool m_useOverrideComputedStyle : 1;
     bool m_needsOverrideComputedStyleUpdate : 1;
     RefPtr<MutableStylePropertySet> m_animatedSMILStyleProperties;
     RefPtr<RenderStyle> m_overrideComputedStyle;
 };
 
 }
 
 #endif