JavaScript and __proto__ - what browsers use it?

Question

What web browsers use the __proto__? Mozilla states that:

Note that __proto__ may not be available in JavaScript versions ot

Answer 1

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Details

The most general way would be to test this page in different browsers:

It alerts if a browser supports __proto__. I've submitted it to browsershots.org, which will create screenshots of the page in many different browsers. Thus, you should see--by means of the alert message--which browser does support it.