Describe the bug
NOTE: This is a bug in the parsing of the Markdown tags by the markdown package. See dart-lang/tools#1279.

The markdown package incorrectly parses Markdown strikethrough tags that are combined with other emphasis tags and the order of the tags changes. This seems to only happen when the inline Markdown tags are in the same text block.

How to reproduce
The following Markdown text:

**~~first~~** ~~**second**~~

Should produce:

first second

But the actual output is:

first ~~second~~

Additional context
This behavior happens with both bold and italic emphasis.