sidedatacopies: get and store sidedata in the changelogrevision object
The object provide a simple way to access changelog entry, we need it to also
bear the sidedata value.
Since the sidedata are retrieved at the same time as the revision, we can do
that without extra cost.
Differential Revision: https://phab.mercurial-scm.org/D6951
{
// 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)
}