upgrade: split actual upgrade code away from the main module
The main module is getting big and hard to follow. So we are splitting all the
logic to actually run an upgrade in a sub module. It nicely highlight that there
are very few actual call point to the code we just moved.
Differential Revision: https://phab.mercurial-scm.org/D9476
{
// Enforcing
"eqeqeq" : true, // true: Require triple equals (===) for comparison
"forin" : true, // true: Require filtering for..in loops with obj.hasOwnProperty()
"freeze" : true, // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
"nonbsp" : true, // true: Prohibit "non-breaking whitespace" characters.
"undef" : true, // true: Require all non-global variables to be declared (prevents global leaks)
// Environments
"browser" : true // Web Browser (window, document, etc)
}