Method is_esr

rust/src/lib.rs:806–808

(&self, browser_version: &str)

    }

    fn is_esr(&self, browser_version: &str) -> bool {
        browser_version.eq_ignore_ascii_case(ESR)
    }

    fn is_unstable(&self, browser_version: &str) -> bool {
        browser_version.eq_ignore_ascii_case(BETA)