Set geometry dirty bits on composited layer mappings when updating squashed layers.

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 2bf77db422f5707a56f4a906df7b2dda6eaa3d09..58c5c0626452914f0dd3bdaeccc84f55e00bff23 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -3556,6 +3556,15 @@ void RenderLayer::clearCompositedLayerMapping(bool layerBeingDestroyed)
         updateOrRemoveFilterEffectRenderer();
 }
 
+void RenderLayer::setGroupedMapping(CompositedLayerMapping* groupedMapping, bool layerBeingDestroyed)
+{
+    if (!layerBeingDestroyed && m_groupedMapping)
+        m_groupedMapping->setNeedsGeometryUpdate();
+    m_groupedMapping = groupedMapping;
+    if (!layerBeingDestroyed && m_groupedMapping)
+        m_groupedMapping->setNeedsGeometryUpdate();
+}
+
 bool RenderLayer::hasCompositedMask() const
 {
     return m_compositedLayerMapping && m_compositedLayerMapping->hasMaskLayer();