Remove externs for Netscapes LiveConnect
Remove externs for Netscapes LiveConnect

It was removed in Firefox 16 and then only used in Java Applets
which support was removed for in major browsers a while ago (2015-2016?).

[1] https://developer.mozilla.org/en-US/docs/Archive/Web/LiveConnect

Remove netscape variable that no longer seems to supported

Closes https://github.com/google/closure-compiler/pull/3350.

PiperOrigin-RevId: 246577992

google/elemental2,google/elemental2