stream-clone: filter possible missing requirements using all supported one
The `supportedformat` requirements is missing some important requirements and it
seems better to filter out with all requirements we know, not just an
"arbitrary" subset.
This is especially relevant as we about to phase out the `supportedformat` class
attribute.
(a backport of this change to stable should be sent soon).
Differential Revision: https://phab.mercurial-scm.org/D12031
{
// 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)
}