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

Source/core/paint/DeprecatedPaintLayerPaintingInfo.h

Index: Source/core/paint/DeprecatedPaintLayerPaintingInfo.h
diff --git a/Source/core/paint/DeprecatedPaintLayerPaintingInfo.h b/Source/core/paint/DeprecatedPaintLayerPaintingInfo.h
index 3a0a8738178c188b962269194035af513250f26a..235d7f8b32979b0f33fa480ee917aefca99af725 100644
--- a/Source/core/paint/DeprecatedPaintLayerPaintingInfo.h
+++ b/Source/core/paint/DeprecatedPaintLayerPaintingInfo.h
@@ -52,6 +52,7 @@ namespace blink {
 
 class DeprecatedPaintLayer;
 class LayoutObject;
+class PaintDataCache;
 
 enum PaintLayerFlag {
     PaintLayerHaveTransparency = 1,
@@ -75,13 +76,14 @@ typedef unsigned PaintLayerFlags;
 struct DeprecatedPaintLayerPaintingInfo {
     DeprecatedPaintLayerPaintingInfo(DeprecatedPaintLayer* inRootLayer, const LayoutRect& inDirtyRect,
         PaintBehavior inPaintBehavior, const LayoutSize& inSubPixelAccumulation,
-        LayoutObject* inPaintingRoot = 0)
+        LayoutObject* inPaintingRoot = 0, PaintDataCache* inPaintDataCache = nullptr)
         : rootLayer(inRootLayer)
         , paintingRoot(inPaintingRoot)
         , paintDirtyRect(inDirtyRect)
         , subPixelAccumulation(inSubPixelAccumulation)
         , paintBehavior(inPaintBehavior)
         , clipToDirtyRect(true)
+        , paintDataCache(inPaintDataCache)
     { }
     DeprecatedPaintLayer* rootLayer;
     LayoutObject* paintingRoot; // only paint descendants of this object
@@ -90,6 +92,7 @@ struct DeprecatedPaintLayerPaintingInfo {
     IntSize scrollOffsetAccumulation;
     PaintBehavior paintBehavior;
     bool clipToDirtyRect;
+    PaintDataCache* paintDataCache;
 };
 
 } // namespace blink