Right now, MdTextButton takes a context param, which in practice is either CONTEXT_BUTTON, or CONTEXT_BUTTON_MD, and defaults to the latter. I'm pretty sure that this is:
- Vestigial from the Harmony/MD/MD refresh changeovers.
- Not a lever we actually want to provide, since in practice, what it means is that we will miss some intended typography code paths and not much else. (See #1 and #4 in  Issue 918194 )