revsetlang: add utility function to return hash like symbols from the tree
Functionalities like unhiding changesets whose rev/hash is passed by the user
required the knowledge of rev/hashes in the user provided specs. This patch adds
functions which can parse tree object and return a list of such values.
Differential Revision: https://phab.mercurial-scm.org/D1732
{
// 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)
}