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

Source/core/paint/PaintInfo.h

Index: Source/core/paint/PaintInfo.h
diff --git a/Source/core/paint/PaintInfo.h b/Source/core/paint/PaintInfo.h
index 910ff358488751632ba70178c2beece4748db4ae..1f4b0b56f399f33f0e598acd7fa26a84f53da594 100644
--- a/Source/core/paint/PaintInfo.h
+++ b/Source/core/paint/PaintInfo.h
@@ -43,11 +43,13 @@ 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)
@@ -55,6 +57,7 @@ struct PaintInfo {
         , paintingRoot(newPaintingRoot)
         , m_paintContainer(newPaintContainer)
         , m_outlineObjects(newOutlineObjects)
+        , m_paintDataCache(newPaintDataCache)
     {
     }
 
@@ -98,6 +101,8 @@ struct PaintInfo {
             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
@@ -108,6 +113,7 @@ struct PaintInfo {
 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