If object does not have key, add it.
Dette scriptet burde ikke installeres direkte. Det er et bibliotek for andre script å inkludere med det nye metadirektivet // @require https://update.greasyfork.org/scripts/427473/937466/object_setDefault.js
Added method setDefault to object prototype.
function setDefault (key, value)
If object does not have key, add it with value value
key (string, required)
key to check
value (any, optional, default = undefined)
value for key if it's not present