Avoid recreating BlockTag pattern on every access
Avoid recreating BlockTag pattern on every access

tomyeh/markd,srawlins/dart-markdown,dart-lang/markdown,dpeek/dart-markdown,dpeek/dart-markdown,dart-lang/markdown,tomyeh/markd,tomyeh/markd,srawlins/dart-markdown,srawlins/dart-markdown,dart-lang/markdown