Is facebook suddenly safe against JSON hijacking?

It is well known that Facebook uses javascript responses (JS,not json) which is prefixes with while(1) & for(;;); in order to prevent script tag to steal the json data when old browsers are being overloaded with their Array ctor & Object ctor.

But from a recent try , it seems that this is not the case anymore (for friends list , which i'm sure it was used)

Notice that now , the content-type is :

content-type: application/octet-stream

But why did they do it ? is it now safe ? ( I know that it's for older browsers , but still...).

I know that [..]'s ctor was problematic. But what about {..}'s ctor ?

Question:

Why did facebook remove the infinite-loop ? and how do they now mitigate against json hijacking ?

I mean , what happens now if <script> tag will try to fetch the "getFiriends "list ? ( in a very old browser)

NB

Worth to mention that there are still others responses with infinite loop for {..} !! :

Also in here ( Object , with infinite loop)

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