Don't clip invalidation of composited scrolling contents

Source/core/rendering/PaintInvalidationState.cpp

Index: Source/core/rendering/PaintInvalidationState.cpp
diff --git a/Source/core/rendering/PaintInvalidationState.cpp b/Source/core/rendering/PaintInvalidationState.cpp
index 0cf83570ef9f92bcf6a1a5b3037c203eac431d87..7a9786d8169ac58ee2caf5477f4bae7a3b7b33c4 100644
--- a/Source/core/rendering/PaintInvalidationState.cpp
+++ b/Source/core/rendering/PaintInvalidationState.cpp
@@ -87,6 +87,15 @@ void PaintInvalidationState::applyClipIfNeeded(const RenderObject& renderer)
         return;
 
     const RenderBox& box = toRenderBox(renderer);
+    m_paintOffset -= box.scrolledContentOffset();
+
+    // Do not clip scroll layer contents because the compositor expects the whole layer
+    // to be always invalidated in-time.
+    if (box.usesCompositedScrolling()) {
+        ASSERT(!m_clipped); // The box should establish paint invalidation container, so no m_clipped inherited.
+        return;
+    }
+
     LayoutRect clipRect(toPoint(m_paintOffset), box.layer()->size());
     if (m_clipped) {
         m_clipRect.intersect(clipRect);
@@ -94,7 +103,6 @@ void PaintInvalidationState::applyClipIfNeeded(const RenderObject& renderer)
         m_clipRect = clipRect;
         m_clipped = true;
     }
-    m_paintOffset -= box.scrolledContentOffset();
 }
 
 } // namespace blink