Reimplement min-width: auto

Source/core/layout/LayoutButton.cpp

 /**
  * Copyright (C) 2005 Apple Computer, 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 48 matching lines @@
     } else {
         m_inner->removeChild(oldChild);
     }
 }
 
 void LayoutButton::updateAnonymousChildStyle(const LayoutObject& child, ComputedStyle& childStyle) const
 {
     ASSERT(!m_inner || &child == m_inner);
 
     childStyle.setFlexGrow(1.0f);
+    // min-width: 0; is needed for correct shrinking.
+    childStyle.setMinWidth(Length(0, Fixed));
     // Use margin:auto instead of align-items:center to get safe centering, i.e.
     // when the content overflows, treat it the same as align-items: flex-start.
     childStyle.setMarginTop(Length());
     childStyle.setMarginBottom(Length());
     childStyle.setFlexDirection(style()->flexDirection());
     childStyle.setJustifyContent(style()->justifyContent());
     childStyle.setFlexWrap(style()->flexWrap());
     childStyle.setAlignItems(style()->alignItems());
     childStyle.setAlignContent(style()->alignContent());
 }
@@ skipping 24 matching lines @@
     return LayoutFlexibleBox::baselinePosition(baseline, firstLine, direction, linePositionMode);
 }
 
 
 // For compatibility with IE/FF we only clip overflow on input elements.
 bool LayoutButton::hasControlClip() const
 {
     return !isHTMLButtonElement(node());
 }
 } // namespace blink