legacy upload.js: Clean up and remove from jshintignore
* Coding style:
- Braces
- Single quotes
- Dot instead of bracket access for properties
* Fixed various implied global/static variables, most significantly
the for-loop variable 'cached' etc.
* Changed == '' to ! since === '' will require it to be a string
and == '' returns true for almost anything that is falsy, no
good way to choose a strict alternative.
* Changed setAttribute('disabled', ..) to using .property instead.
* Using setTimeout as a global instead of as a window property.
* Using other globals from wikibits.js through window property,
as they are defined.
* Use a closure instead of string eval() in setTimeout().
* Made local equivalents for some global variables for access
inside the closure.
* Don't create functions in a loop. Moved the onchange function
outside the loop and re-used it for each one (safe in this case,
and more efficient).
* Call setTimeout/clearTimeout as global, no need for the window
object as host.
Change-Id: I9df912ee48d30c189394bf07f5e49014220f36a3