Traverse into child LayoutViews during invalidateTreeIfNeeded

Source/core/layout/LayoutPart.cpp

Index: Source/core/layout/LayoutPart.cpp
diff --git a/Source/core/layout/LayoutPart.cpp b/Source/core/layout/LayoutPart.cpp
index cae3fb991c9aa9970659e306f186f9fd9452063c..b48e96f211f7bb0a03c62d7fd7bd339f7dadc0ab 100644
--- a/Source/core/layout/LayoutPart.cpp
+++ b/Source/core/layout/LayoutPart.cpp
@@ -331,4 +331,15 @@ bool LayoutPart::setWidgetGeometry(const LayoutRect& frame)
     return widget->frameRect().size() != newFrame.size();
 }
 
+void LayoutPart::invalidatePaintOfSubtreesIfNeeded(PaintInvalidationState& paintInvalidationState)
+{
+    if (widget() && widget()->isFrameView()) {
+        FrameView* childFrameView = toFrameView(widget());
+        PaintInvalidationState childViewPaintInvalidationState(paintInvalidationState, *childFrameView->layoutView(), paintInvalidationState.paintInvalidationContainer());
+        toFrameView(widget())->invalidateTreeIfNeeded(childViewPaintInvalidationState);
+    }
+
+    LayoutReplaced::invalidatePaintOfSubtreesIfNeeded(paintInvalidationState);
+}
+
 }