Enforce clearing renderers' paint invalidation state

Source/core/rendering/RenderObject.cpp

Index: Source/core/rendering/RenderObject.cpp
diff --git a/Source/core/rendering/RenderObject.cpp b/Source/core/rendering/RenderObject.cpp
index f58c8cdcb0b59e57de5b93ecb19983d730a804b8..6a6f83e19b7eaf5ab404a4ce132e23413144530b 100644
--- a/Source/core/rendering/RenderObject.cpp
+++ b/Source/core/rendering/RenderObject.cpp
@@ -3395,6 +3395,9 @@ bool RenderObject::isRelayoutBoundaryForInspector() const
 
 void RenderObject::clearPaintInvalidationState()
 {
+    // paintInvalidationStateIsDirty should be kept in sync with the
+    // booleans that are cleared below.
+    ASSERT(paintInvalidationStateIsDirty());
     setShouldDoFullPaintInvalidation(false);
     setShouldDoFullPaintInvalidationIfSelfPaintingLayer(false);
     setOnlyNeededPositionedMovementLayout(false);