Keep a cache of caret painters to avoid recomputing all the time.

Source/core/paint/PaintInfo.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google 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
@@ skipping 25 matching lines @@
 #include "wtf/HashMap.h"
 #include "wtf/ListHashSet.h"
 
 #include <limits>
 
 namespace blink {
 
 class LayoutInline;
 class LayoutBoxModelObject;
 class LayoutObject;
+class PaintDataCache;
 
 struct PaintInfo {
     PaintInfo(GraphicsContext* newContext, const IntRect& newRect, PaintPhase newPhase, PaintBehavior newPaintBehavior,
         LayoutObject* newPaintingRoot = 0, ListHashSet<LayoutInline*>* newOutlineObjects = 0,
-        const LayoutBoxModelObject* newPaintContainer = 0)
+        const LayoutBoxModelObject* newPaintContainer = 0,
+        PaintDataCache* newPaintDataCache = nullptr)
         : context(newContext)
         , rect(newRect)
         , phase(newPhase)
         , paintBehavior(newPaintBehavior)
         , paintingRoot(newPaintingRoot)
         , m_paintContainer(newPaintContainer)
         , m_outlineObjects(newOutlineObjects)
+        , m_paintDataCache(newPaintDataCache)
     {
     }
 
     void updatePaintingRootForChildren(const LayoutObject* layoutObject)
     {
         if (!paintingRoot)
             return;
 
         // If we're the painting root, kids draw normally, and see root of 0.
         if (paintingRoot == layoutObject) {
@@ skipping 23 matching lines @@
     {
         return transform.mapRect(boundingBox).intersects(rect);
     }
 
     void updateCullRectForSVGTransform(const AffineTransform& localToParentTransform)
     {
         if (rect != LayoutRect::infiniteIntRect())
             rect = localToParentTransform.inverse().mapRect(rect);
     }
 
+    PaintDataCache* paintDataCache() const { return m_paintDataCache; }
+
     // FIXME: Introduce setters/getters at some point. Requires a lot of changes throughout layout/.
     GraphicsContext* context;
     IntRect rect; // dirty rect used for culling non-intersecting layoutObjects
     PaintPhase phase;
     PaintBehavior paintBehavior;
     LayoutObject* paintingRoot; // used to draw just one element and its visual kids
 
 private:
     const LayoutBoxModelObject* m_paintContainer; // the box model object that originates the current painting
     ListHashSet<LayoutInline*>* m_outlineObjects; // used to list outlines that should be painted by a block with inline children
+    PaintDataCache* m_paintDataCache; // caches information frequently needed during paint
 };
 
 } // namespace blink
 
 #endif // PaintInfo_h