update sort for load

Author: austinEng

Source/Scene/Cesium3DTileset.js

@@ -1164,15 +1164,7 @@ define([
             return diff;
         }
 
-        var ancestorA = a._ancestorWithLoadedContent;
-        var ancestorB = b._ancestorWithLoadedContent;
-
-        if (ancestorA === ancestorB) {
-            return diff;
-        }
-
-        var screenSpaceErrorDiff = b._screenSpaceError - a._screenSpaceError;
-        return screenSpaceErrorDiff === 0 ? diff : screenSpaceErrorDiff;
+        return b._screenSpaceError - a._screenSpaceError;
     }
 
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