Add position sticky main thread scrolling reason [spv2]

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

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index 845feea8a627810653cb95f2e49a9ce2f57007a0..ad2383be01be9ddad3a5422c30ff64f0e4c90d28 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -342,6 +342,13 @@ void PaintPropertyTreeBuilder::updateMainThreadScrollingReasons(const LayoutObje
             scrollNode = scrollNode->parent();
         }
     }
+    if (object.styleRef().position() == StickyPosition) {
+        auto* scrollNode = context.current.scroll;
+        while (scrollNode && !scrollNode->hasMainThreadScrollingReasons(MainThreadScrollingReason::kHasStickyPositionObjects)) {
+            scrollNode->addMainThreadScrollingReasons(MainThreadScrollingReason::kHasStickyPositionObjects);
+            scrollNode = scrollNode->parent();
+        }
+    }
 }
 
 void PaintPropertyTreeBuilder::updateOverflowClip(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)