Avoid N^2 walk placing renderers when building the render tree

Source/core/css/resolver/StyleResolverState.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 26 matching lines @@
 namespace WebCore {
 
 class FontDescription;
 class RenderRegion;
 
 class StyleResolverState {
 WTF_MAKE_NONCOPYABLE(StyleResolverState);
 public:
     StyleResolverState()
     : m_element(0)
+    , m_childIndex(0)
     , m_styledElement(0)
     , m_parentNode(0)
     , m_parentStyle(0)
     , m_rootElementStyle(0)
     , m_regionForStyling(0)
     , m_elementLinkState(NotInsideLink)
     , m_distributedToInsertionPoint(false)
     , m_elementAffectedByClassRules(false)
     , m_applyPropertyToRegularStyle(true)
     , m_applyPropertyToVisitedLinkStyle(false)
     , m_lineHeightValue(0)
     , m_fontDirty(false)
     , m_styleMap(*this, m_elementStyleResources)
     { }
 
-public:
-    void initForStyleResolve(Document*, Element*, RenderStyle* parentStyle = 0, RenderRegion* regionForStyling = 0);
+    void initForStyleResolve(Document*, Element*, int childIndex = 0, RenderStyle* parentStyle = 0, RenderRegion* regionForStyling = 0);
     void clear();
 
     Document* document() const { return m_element->document(); }
     Element* element() const { return m_element; }
+    int childIndex() const { return m_childIndex; }
     Element* styledElement() const { return m_styledElement; }
     void setStyle(PassRefPtr<RenderStyle> style) { m_style = style; }
     RenderStyle* style() const { return m_style.get(); }
     PassRefPtr<RenderStyle> takeStyle() { return m_style.release(); }
 
     const ContainerNode* parentNode() const { return m_parentNode; }
     void setParentStyle(PassRefPtr<RenderStyle> parentStyle) { m_parentStyle = parentStyle; }
     RenderStyle* parentStyle() const { return m_parentStyle.get(); }
     RenderStyle* rootElementStyle() const { return m_rootElementStyle; }
 
@@ skipping 56 matching lines @@
     // of each individual length value in the render style / tree. CSSPrimitiveValue::computeLength*()
     // multiplies each resolved length with the zoom multiplier - so for SVG we need to disable that.
     // Though all CSS values that can be applied to outermost <svg> elements (width/height/border/padding...)
     // need to respect the scaling. RenderBox (the parent class of RenderSVGRoot) grabs values like
     // width/height/border/padding/... from the RenderStyle -> for SVG these values would never scale,
     // if we'd pass a 1.0 zoom factor everyhwere. So we only pass a zoom factor of 1.0 for specific
     // properties that are NOT allowed to scale within a zoomed SVG document (letter/word-spacing/font-size).
     bool useSVGZoomRules() const { return m_element && m_element->isSVGElement(); }
 
 private:
-    void initElement(Element*);
+    void initElement(Element*, int childIndex);
 
     Element* m_element;
+    int m_childIndex;
     RefPtr<RenderStyle> m_style;
     Element* m_styledElement;
     ContainerNode* m_parentNode;
     RefPtr<RenderStyle> m_parentStyle;
     RenderStyle* m_rootElementStyle;
 
     // Required to ASSERT in applyProperties.
     RenderRegion* m_regionForStyling;
 
     EInsideLink m_elementLinkState;
@@ skipping 11 matching lines @@
     CachedUAStyle m_cachedUAStyle;
     ElementStyleResources m_elementStyleResources;
     // CSSToStyleMap is a pure-logic class and only contains
     // a back-pointer to this object.
     CSSToStyleMap m_styleMap;
 };
 
 } // namespace WebCore
 
 #endif // StyleResolverState_h