Firefox error: mutating the [[Prototype]] of an object


my application is running fine in Google Chrome but when I run it in Firefox (version 35) I get the following error message:

mutating the [[Prototype]] of an object will
cause your code to run very slowly; instead create the object with
the correct initial [[Prototype]] value using Object.create

I think this is not a real problem, but I’m writing my major project for my studies and I have to give some information, why this error occurs. I searched for appearances for the problematic proto and found two usages in the Cesium.js (unminified) file on line 126522: 185 and on line 126522: 213.
I would be grateful for an explanation, which I can quote in my work.

Best regards,


It’s not an error message, it’s a warning specific to Firefox triggered by Knockout,, a third-party library used for data-binding in our widgets. It can be safely ignored. Contact the knockout team if you would like further explanation.