Function fastKey

test/fixtures/compile-performance.js:8107–8119

(it, create)

            }});
        };
        var fastKey = function(it, create){
            // return primitive with prefix
            if(!isObject(it))return typeof it == 'symbol' ? it : (typeof it == 'string' ? 'S' : 'P') + it;
            if(!has(it, META)){
                // can't set metadata to uncaught frozen object
                if(!isExtensible(it))return 'F';
                // not necessary to add metadata
                if(!create)return 'E';
                // add missing metadata
                setMeta(it);
                // return object ID
            } return it[META].i;
        };
        var getWeak = function(it, create){
            if(!has(it, META)){
                // can't set metadata to uncaught frozen object