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

Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp

Index: Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
diff --git a/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp b/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
index 70d7cfb92555ba4fbfc0add3d8b7a03ecfbbd000..3698af81bd4d8cb2f54abf40187342a8092fbe7f 100644
--- a/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
+++ b/Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp
@@ -50,6 +50,7 @@
 #include "core/page/scrolling/ScrollingCoordinator.h"
 #include "core/paint/DeprecatedPaintLayerPainter.h"
 #include "core/paint/DeprecatedPaintLayerStackingNodeIterator.h"
+#include "core/paint/PaintDataCache.h"
 #include "core/paint/ScrollableAreaPainter.h"
 #include "core/paint/TransformRecorder.h"
 #include "core/plugins/PluginView.h"
@@ -2112,16 +2113,17 @@ void CompositedDeprecatedPaintLayerMapping::doPaintTask(const GraphicsLayerPaint
     float deviceScaleFactor = blink::deviceScaleFactor(paintInfo.paintLayer->layoutObject()->frame());
     context->setDeviceScaleFactor(deviceScaleFactor);
 
+    PaintDataCache paintDataCache;
+    DeprecatedPaintLayerPaintingInfo paintingInfo(paintInfo.paintLayer, LayoutRect(dirtyRect), PaintBehaviorNormal, paintInfo.paintLayer->subpixelAccumulation(), nullptr, &paintDataCache);
+    DeprecatedPaintLayerPainter painter(*paintInfo.paintLayer);
+
     if (paintInfo.paintLayer->compositingState() != PaintsIntoGroupedBacking) {
         // FIXME: GraphicsLayers need a way to split for multicol.
-        DeprecatedPaintLayerPaintingInfo paintingInfo(paintInfo.paintLayer, LayoutRect(dirtyRect), PaintBehaviorNormal, paintInfo.paintLayer->subpixelAccumulation());
-        DeprecatedPaintLayerPainter(*paintInfo.paintLayer).paintLayerContents(context, paintingInfo, paintLayerFlags);
+        painter.paintLayerContents(context, paintingInfo, paintLayerFlags);
 
         if (paintInfo.paintLayer->containsDirtyOverlayScrollbars())
-            DeprecatedPaintLayerPainter(*paintInfo.paintLayer).paintLayerContents(context, paintingInfo, paintLayerFlags | PaintLayerPaintingOverlayScrollbars);
+            painter.paintLayerContents(context, paintingInfo, paintLayerFlags | PaintLayerPaintingOverlayScrollbars);
     } else {
-        DeprecatedPaintLayerPaintingInfo paintingInfo(paintInfo.paintLayer, LayoutRect(dirtyRect), PaintBehaviorNormal, paintInfo.paintLayer->subpixelAccumulation());
-
         // DeprecatedPaintLayer::paintLayer assumes that the caller clips to the passed rect. Squashed layers need to do this clipping in software,
         // since there is no graphics layer to clip them precisely. Furthermore, in some cases we squash layers that need clipping in software
         // from clipping ancestors (see CompositedDeprecatedPaintLayerMapping::localClipRectForSquashedLayer()).
@@ -2138,7 +2140,7 @@ void CompositedDeprecatedPaintLayerMapping::doPaintTask(const GraphicsLayerPaint
                 clipDisplayItem.replay(*context);
             }
         }
-        DeprecatedPaintLayerPainter(*paintInfo.paintLayer).paintLayer(context, paintingInfo, paintLayerFlags);
+        painter.paintLayer(context, paintingInfo, paintLayerFlags);
         {
             if (context->displayItemList()) {
                 ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());