[MD] Pass correct parameter to HtmlRenderer
[MD] Pass correct parameter to HtmlRenderer

blackfriday.HtmlRenderer is using HTML tags and not Markdown extensions as
parameters. Passing thus common HTML tags instead (matching commonHtmlFlags
from blackfriday).

The invalid matches were making images (index of HTML_SKIP_IMAGES was matching
EXTENSION_FENCED_CODE) skipped from Markdown.

googlecodelabs/tools,googlecodelabs/tools,chrisrecher/tools,Qwiklabs/codelab-tools,CloudVLab/tools,Qwiklabs/codelab-tools,Qwiklabs/codelab-tools,chrisrecher/tools,CloudVLab/tools,Qwiklabs/codelab-tools,googlecodelabs/tools,googlecodelabs/tools