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 98d62c8c2fa164070698f109a86f51b53d277f0e..7746fdc31f2d7ef111a8884fb892dbf61b7c2ee7 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -345,6 +345,13 @@ 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)