.jshintrc

rust: less set lookups in AncestorsIterator

This uses the boolean return of `HashSet::insert()` to factor
pairs of contains()/insert() into a single insert()

On the mozilla-central repository (450k changesets), I get about a bit more
than 10% better medians in perfancestors (taking the mean of three runs)

Best run for parent changeset:

! wall 0.106474 comb 0.110000 user 0.110000 sys 0.000000 (median of 93)

Best run for this changeset:

! wall 0.093191 comb 0.090000 user 0.090000 sys 0.000000 (median of 100)

Differential Revision: https://phab.mercurial-scm.org/D5942

{
    // 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)
}