Fix SELECT element width with the mock theme.

third_party/WebKit/Source/core/layout/LayoutThemeDefault.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 321 matching lines @@
 
 int LayoutThemeDefault::popupInternalPaddingBottom(
     const ComputedStyle& style) const {
   return menuListInternalPadding(style, 1);
 }
 
 // static
 int LayoutThemeDefault::scrollbarThicknessInDIP() {
   int width = Platform::current()
                   ->themeEngine()
-                  ->getSize(WebThemeEngine::PartScrollbarDownArrow)
+                  ->getSize(WebThemeEngine::PartScrollbarUpArrow)
                   .width;
   return width > 0 ? width : 15;
 }
 
 // static
 float LayoutThemeDefault::clampedMenuListArrowPaddingSize(
     const HostWindow* host,
     const ComputedStyle& style) {
   int originalSize = scrollbarThicknessInDIP();
   int scaledSize =
@@ skipping 29 matching lines @@
 double LayoutThemeDefault::animationRepeatIntervalForProgressBar() const {
   return progressAnimationInterval;
 }
 
 double LayoutThemeDefault::animationDurationForProgressBar() const {
   return progressAnimationInterval * progressAnimationFrames *
          2;  // "2" for back and forth
 }
 
 }  // namespace blink