dirstate-map: factor out the change to _dirs and _alldirs on adding
This logic is complicated enough to deserves its own function. So it now does.
This will make it easier to reuse that logic in later changeset.
Differential Revision: https://phab.mercurial-scm.org/D11129
{
// 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)
}