Remove Nashorn-specific comment
Remove Nashorn-specific comment

I couldn't reproduce a case of Nashorn returning null for a non-existent
property, of either a Java object or a JavaScript object, even going
back to Java 8u20. But the test makes sense in any case, so I just
removed the mention of Nashorn.

ut7/ScriptCraft,ut7/ScriptCraft,walterhiggins/ScriptCraft,walterhiggins/ScriptCraft