Fix crash when resizing a view destroys the render tree

Source/core/svg/graphics/SVGImage.cpp

 /*
  * Copyright (C) 2006 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 105 matching lines @@
 
 void SVGImage::setContainerSize(const IntSize& size)
 {
     if (!m_page || !usesContainerSize())
         return;
 
     LocalFrame* frame = m_page->mainFrame();
     SVGSVGElement* rootElement = toSVGDocument(frame->document())->rootElement();
     if (!rootElement)
         return;
-    RenderSVGRoot* renderer = toRenderSVGRoot(rootElement->renderer());
-    if (!renderer)
-        return;
 
     FrameView* view = frameView();
     view->resize(this->containerSize());
 
+    RenderSVGRoot* renderer = toRenderSVGRoot(rootElement->renderer());
+    if (!renderer)
+        return;
     renderer->setContainerSize(size);
 }
 
 IntSize SVGImage::containerSize() const
 {
     if (!m_page)
         return IntSize();
     LocalFrame* frame = m_page->mainFrame();
     SVGSVGElement* rootElement = toSVGDocument(frame->document())->rootElement();
     if (!rootElement)
@@ skipping 271 matching lines @@
 
     return m_page;
 }
 
 String SVGImage::filenameExtension() const
 {
     return "svg";
 }
 
 }