Remove -webkit-appearance:default-button. This was only used in Safari.

Source/core/rendering/RenderThemeChromiumDefault.cpp

 /*
  * Copyright (C) 2007 Apple Inc.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Collabora Ltd.
  * Copyright (C) 2008, 2009 Google Inc.
  * Copyright (C) 2009 Kenneth Rohde Christiansen
  *
  * 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
@@ skipping 235 matching lines @@
         return;
 
     IntSize size = WebKit::Platform::current()->themeEngine()->getSize(WebKit::WebThemeEngine::PartRadio);
     setSizeIfAuto(style, size);
 }
 
 bool RenderThemeChromiumDefault::paintButton(RenderObject* o, const PaintInfo& i, const IntRect& rect)
 {
     WebKit::WebThemeEngine::ExtraParams extraParams;
     WebKit::WebCanvas* canvas = i.context->platformContext()->canvas();
-    extraParams.button.isDefault = isDefault(o);
     extraParams.button.hasBorder = true;
     extraParams.button.backgroundColor = defaultButtonBackgroundColor;
     if (o->hasBackground())
         extraParams.button.backgroundColor = o->style()->visitedDependentColor(CSSPropertyBackgroundColor).rgb();
 
     WebKit::Platform::current()->themeEngine()->paint(canvas, WebKit::WebThemeEngine::PartButton, getWebThemeState(this, o), WebKit::WebRect(rect), &extraParams);
     return false;
 }
 
 bool RenderThemeChromiumDefault::paintTextField(RenderObject* o, const PaintInfo& i, const IntRect& rect)
@@ skipping 112 matching lines @@
     WebKit::Platform::current()->themeEngine()->paint(canvas, WebKit::WebThemeEngine::PartProgressBar, getWebThemeState(this, o), WebKit::WebRect(rect), &extraParams);
     return false;
 }
 
 bool RenderThemeChromiumDefault::shouldOpenPickerWithF4Key() const
 {
     return true;
 }
 
 } // namespace WebCore