upgrade: add support for experimental safe share mode
Recently we introduce the share-safe functionality which makes shares share
requirements and config of share source. This patch adds support to
`debugupgraderepo` command to upgrade repository to share-safe mode when
`format.exp-share-safe` config is enabled.
Differential Revision: https://phab.mercurial-scm.org/D9144
{
// 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)
}