Only store previous clip rects for PaintLayers that support subsequences.

third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp

Index: third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp
diff --git a/third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp b/third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp
index a66c093bc1c40fc68278c24baa6c1899cb9cf658..e4944c4f5c4227984f40a32f7f918af43200f253 100644
--- a/third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp
+++ b/third_party/WebKit/Source/core/paint/PrePaintTreeWalk.cpp
@@ -157,6 +157,14 @@ void PrePaintTreeWalk::InvalidatePaintLayerOptimizationsIfNeeded(
     context.ancestor_transformed_or_root_paint_layer = &paint_layer;
   }
 
+  // This code below checks whether any clips have changed that might:
+  // (a) invalidate optimizations made for a PaintLayer that supports
+  //     subsequence caching, or
+  // (b) impact clipping of descendant visual rects.
+  if (!paint_layer.SupportsSubsequenceCaching() &&
+      !paint_layer.GetLayoutObject().HasClipRelatedProperty())
+    return;
+
   const auto& ancestor =
       context.ancestor_transformed_or_root_paint_layer->GetLayoutObject();
   PropertyTreeState ancestor_state = *ancestor.LocalBorderBoxProperties();