phases: use revision number in `_pushdiscoveryphase`
We now reach our target checkpoint in terms of rev-num conversion. The
`_pushdiscoveryphase` function is now performing graph computation based on
revision number only. Avoiding repeated conversion from node-id to rev-num.
See previous changeset updated `new_heads` for rationnal.
Again, time saved in the 100 milliseconds order of magnitude for the mozilla-try
benchmark I have been using.
However, wow that the logic is done using revision number, we can look into having
better logic in the next changesets, which will provide a much bigger speedup.
{
// 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)
}