[Representation] Minimize scope reuse

When switching among domain objects and/or views, avoid
reusing the same information is scope. The wrong information
in scope can cause various failures in views, such as WTD-1182.

platform/features/layout/src/LayoutController.js

@@ -69,6 +69,9 @@ define(
             function lookupPanels(ids) {
                 var configuration = $scope.configuration || {};
 
+                // Ensure ids is array-like
+                ids = ids || [];
+
                 // Pull panel positions from configuration
                 rawPositions = shallowCopy(configuration.panels || {}, ids);