Improve BlockquoteSyntax (dart-lang/markdown#479)

* Improve BlockquoteSyntax

* Fix a comment

* Fix a FencedCodeBlockSyntax issue

It was not an issue until merged this updated FencedCodeBlockSyntax into current branch
11 files changed
tree: b6c9a8866ccda91c9e482dbd558b8f203591ed88
  1. pkgs/