fix: this.outro need to be mapped

[hai-x]

const s = new MagicString(
  'var answer = 42;\nconsole.log("the answer is %s", answer);'
)
s.append('\n\n\n\n}).call(global);')

Then s.toString().split('\n').length equals to 6, which means output has 6 lines.

So for its sourcemap, s.generateMap().mappings should also has 6 lines. But now it only has 2 lines.

Current output

AAAA;AACA

Expected output

AAAA;AACA;;;;

[antfu]

Could you help to add a test to guard this from future regressions? Thanks

[hai-x]

Could you help to add a test to guard this from future regressions? Thanks

@antfu Added. Could you please review it again?