Fixed an error where stage could not take screenshots

objects.js

@@ -4868,6 +4868,12 @@ StageMorph.prototype.deleteVariable = SpriteMorph.prototype.deleteVariable;
 StageMorph.prototype.doScreenshot
     = SpriteMorph.prototype.doScreenshot;
 
+StageMorph.prototype.newCostumeNameCached
+    = SpriteMorph.prototype.newCostumeNameCached;
+
+StageMorph.prototype.newCostumeNameFn
+    = SpriteMorph.prototype.newCostumeNameFn;
+
 StageMorph.prototype.blockForSelector
     = SpriteMorph.prototype.blockForSelector;