Remove a bunch of fixed position dead code.

sky/engine/core/rendering/compositing/CompositedLayerMapping.cpp

Index: sky/engine/core/rendering/compositing/CompositedLayerMapping.cpp
diff --git a/sky/engine/core/rendering/compositing/CompositedLayerMapping.cpp b/sky/engine/core/rendering/compositing/CompositedLayerMapping.cpp
index ea1219cac4c8080c0504c53b5f23d3f5e717a941..9c7af6701cc3f65ddd6eb6ec04f8568672bbbb57 100644
--- a/sky/engine/core/rendering/compositing/CompositedLayerMapping.cpp
+++ b/sky/engine/core/rendering/compositing/CompositedLayerMapping.cpp
@@ -921,13 +921,13 @@ void CompositedLayerMapping::updateBackgroundLayerGeometry(const FloatSize& rela
 
 void CompositedLayerMapping::registerScrollingLayers()
 {
+    // FIXME(sky): Remove this whole function. I think this doesn't do anything now that we don't support position:fixed.
+
     // Register fixed position layers and their containers with the scrolling coordinator.
     ScrollingCoordinator* scrollingCoordinator = scrollingCoordinatorFromLayer(m_owningLayer);
     if (!scrollingCoordinator)
         return;
 
-    scrollingCoordinator->updateLayerPositionConstraint(&m_owningLayer);
-
     // Page scale is applied as a transform on the root render view layer. Because the scroll
     // layer is further up in the hierarchy, we need to avoid marking the root render view
     // layer as a container.