exchange: move _computeellipsis() from narrow
This is also referenced as part of the narrow changegroup code and
therefore needs to move to core before we can integrate the narrow
changegroup code into core.
Differential Revision: https://phab.mercurial-scm.org/D4009
{
// 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)
}