HTML macro attributes are corrupted when rendering to CommonMark Markdown 1.2

When rendering an HTML macro to markdown/1.2, the Markdown escaping is applied to the whole HTML content, including tag attributes. Since Markdown doesn't process backslash escapes inside HTML tags, the attribute values are modified.

Steps to reproduce

Render the following xwiki/2.1 content to markdown/1.2:

{{html}}<a href="x_y">a*b</a>{{/html}}

Result

<a href="x\_y">a\*b</a>

The link now points to x_y instead of x_y.

Expected

The HTML tags (and their attributes) are output verbatim; only the text content is escaped where needed.