Do not crash if custom scrollbars have -webkit-appearane:searchfield-foo.

Source/core/rendering/RenderThemeChromiumMac.mm

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Google, Inc.
  *
  * 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,
@@ skipping 1645 matching lines @@
     style->setPaddingTop(Length(verticalPadding, Fixed));
     style->setPaddingBottom(Length(verticalPadding, Fixed));
 
     setFontFromControlSize(style, controlSize);
 
     style->setBoxShadow(nullptr);
 }
 
 bool RenderThemeChromiumMac::paintSearchFieldCancelButton(RenderObject* o, const PaintInfo& paintInfo, const IntRect& r)
 {
+    if (!o->node())
+        return false;
     Element* input = o->node()->shadowHost();
     if (!input)
         input = toElement(o->node());
 
     if (!input->renderer()->isBox())
         return false;
 
     GraphicsContextStateSaver stateSaver(*paintInfo.context);
 
     float zoomLevel = o->style()->effectiveZoom();
@@ skipping 78 matching lines @@
 void RenderThemeChromiumMac::adjustSearchFieldResultsDecorationStyle(RenderStyle* style, Element*) const
 {
     IntSize size = sizeForSystemFont(style, resultsButtonSizes());
     style->setWidth(Length(size.width(), Fixed));
     style->setHeight(Length(size.height(), Fixed));
     style->setBoxShadow(nullptr);
 }
 
 bool RenderThemeChromiumMac::paintSearchFieldResultsDecoration(RenderObject* o, const PaintInfo& paintInfo, const IntRect& r)
 {
+    if (!o->node())
+        return false;
     Node* input = o->node()->shadowHost();
     if (!input)
         input = o->node();
     if (!input->renderer()->isBox())
         return false;
 
     GraphicsContextStateSaver stateSaver(*paintInfo.context);
 
     float zoomLevel = o->style()->effectiveZoom();
     FloatRect unzoomedRect(r);
@@ skipping 237 matching lines @@
 
 bool RenderThemeChromiumMac::shouldUseFallbackTheme(RenderStyle* style) const
 {
     ControlPart part = style->appearance();
     if (part == CheckboxPart || part == RadioPart)
         return style->effectiveZoom() != 1;
     return false;
 }
 
 } // namespace WebCore