change self to window

[SeyyedKhandon]

[BPreisner]

@JSmith01 could you please approve?

[BPreisner]

@SeyyedKhandon I would also suggest a change so this will get a chance to run in CI environments. I mean the self in the IIFE invocation can be completely removed, and I would rather go for the check at the begging of the function body:

if (typeof self === 'undefined') {
    return null;
} 

... rename global to self in the function body

[SeyyedKhandon]

@JSmith01 @GreLI