Function builtin_name 

pub fn builtin_name(key: &str) -> &str

The name a builtin function reports. The table answers for an intrinsic; anything else falls back to the last segment of the key, which is what the name is for every builtin this frontend synthesizes: @proto:TypedArray:set is set and fs.readFileSync is readFileSync. Reporting the whole key was how [Function: @proto:TypedArray:set] reached console.log.