swc_ecma_preset_env/corejs2/builtin.rs
use once_cell::sync::Lazy;
use swc_common::collections::AHashMap;
use crate::{BrowserData, Versions};
pub(crate) static BUILTINS: Lazy<AHashMap<String, Versions>> = Lazy::new(|| {
let map: AHashMap<_, BrowserData<Option<String>>> =
serde_json::from_str(include_str!("builtin.json")).expect("failed to parse json");
map.into_iter()
.map(|(feature, version)| {
(
feature,
version.map_value(|version| version.map(|v| v.parse().unwrap())),
)
})
.collect()
});