Detranspilerization tweaks for JavaScript examples

[insin]

Tweaked JavaScript examples to look a little bit more like they'd be written by hand:

1. Started out with function declarations in example 1, so example 2 implicitly demonstrates moving from declarations to expressions.
2. Made pop() use a function scoped variable instead of the transpilation of the defensive use of do.
3. Switched examples 3 and 4 to return the function-holding object directly, as a progression from example 2's declare and return.