Add helper for computing outset for 'outline'

Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  *
  * 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.
  *
@@ skipping 23 matching lines @@
 #include "core/style/PathStyleMotionPath.h"
 #include "core/style/QuotesData.h"
 #include "core/style/ShadowList.h"
 #include "core/style/StyleImage.h"
 #include "core/style/StyleInheritedData.h"
 #include "platform/LengthFunctions.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/fonts/Font.h"
 #include "platform/fonts/FontSelector.h"
 #include "platform/geometry/FloatRoundedRect.h"
+#include "platform/graphics/GraphicsContext.h"
 #include "wtf/MathExtras.h"
 
 #include <algorithm>
 
 namespace blink {
 
 struct SameSizeAsBorderValue {
     RGBA32 m_color;
     unsigned m_width;
 };
@@ skipping 1550 matching lines @@
 {
     ASSERT(path);
     rareNonInheritedData.access()->m_transform.access()->m_motion.m_path = path;
 }
 
 void ComputedStyle::resetMotionPath()
 {
     rareNonInheritedData.access()->m_transform.access()->m_motion.m_path = nullptr;
 }
 
+int ComputedStyle::outlineOutset() const
+{
+    if (!hasOutline())
+        return 0;
+    if (outlineStyleIsAuto())
+        return GraphicsContext::focusRingOutsetExtent(outlineOffset(), outlineWidth());
+    return outlineSize();
+}
+
 bool ComputedStyle::columnRuleEquivalent(const ComputedStyle* otherStyle) const
 {
     return columnRuleStyle() == otherStyle->columnRuleStyle()
         && columnRuleWidth() == otherStyle->columnRuleWidth()
         && visitedDependentColor(CSSPropertyWebkitColumnRuleColor) == otherStyle->visitedDependentColor(CSSPropertyWebkitColumnRuleColor);
 }
 
 TextEmphasisMark ComputedStyle::textEmphasisMark() const
 {
     TextEmphasisMark mark = static_cast<TextEmphasisMark>(rareInheritedData->textEmphasisMark);
@@ skipping 114 matching lines @@
 }
 
 void ComputedStyle::copyChildDependentFlagsFrom(const ComputedStyle& other)
 {
     setEmptyState(other.emptyState());
     if (other.hasExplicitlyInheritedProperties())
         setHasExplicitlyInheritedProperties();
 }
 
 } // namespace blink