\math??{} font styles are ignored in 2.x #5998
Description
The STIX Fonts Demo shows three Blackboard entries with the same font. In the 1.5.x line, these entries are italic, regular and bold. Additionally, the last three characters in the top row of circled numbers should be bold as well.
A bisect points to 4a2a186 as the first bad commit, the merging of #5214, so ping @zblz.