copies: split the combination of the copies mapping in its own function
In some case, this part take up to 95% of the copy tracing that take about a
hundred second. This poor performance comes from the fact we keep duplciating
and merging dictionary that are mostly similar.
I want to experiment with smarter native code to do this, so I need to isolate
the function first.
{
// 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)
}