feat: test case for constructor comments.
feat: test case for constructor comments.

These were always generated, but only if there is a line break before the
comment start, as otherwise TS considers the comment to belong to the pre-
ceding token.

jeffbcross/ts2dart,dart-archive/ts2dart,hterkelsen/ts2dart,caitp/ts2dart,jacob314/ts2dart,dart-archive/ts2dart,jacob314/ts2dart,dart-archive/ts2dart,hansl/ts2dart,caitp/ts2dart,vicb/ts2dart,yjbanov/ts2dart,jteplitz602/ts2dart,yjbanov/ts2dart,alfonso-presa/ts2dart,jteplitz602/ts2dart,vicb/ts2dart,jeffbcross/ts2dart,alfonso-presa/ts2dart,hansl/ts2dart,hterkelsen/ts2dart