rust-dirstatemap: add missing @propertycache
While investigating a regression on `hg update` performance introduced by the
Rust `dirstatemap`, two missing `@propertycache` were identified when comparing
against the Python implementation. This adds back the first one, that has
no observable impact on behavior. The second one (`nonnormalset`) is going to
be more involved, as the caching has to be done from the Rust side of things.
Differential Revision: https://phab.mercurial-scm.org/D8047
{
// 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)
}