Properly repaint RenderLayer's descendants when it moves

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index b3199f8a10a57700ffeb7a1761da4f42cb5ab1bc..35a65f4e7d823d54060f24c4235b99759e0c2702 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -259,7 +259,11 @@ void RenderLayer::updateLayerPositionsAfterLayout(const RenderLayer* rootLayer,
 
 void RenderLayer::updateLayerPositionRecursive(UpdateLayerPositionsFlags flags)
 {
-    updateLayerPosition();
+    if (flags & ForceMayNeedPaintInvalidation)
+        m_renderer->setMayNeedPaintInvalidation(true);
+
+    if (updateLayerPosition())
+        flags |= ForceMayNeedPaintInvalidation;
 
     // Clear our cached clip rect information.
     m_clipper.clearClipRects();