Inline expectation tests: accept // $MISSING: and // $SPURIOUS:

[smowton]

Previously there had to be a space after the $ token, unlike ordinary expectations (i.e., // $xss was already accepted)

This is an improvement on the fix already shown in #6087 suggested by @aschackmull

[tausbn]

To be honest, I think it would be better to instead require a space after the $. To me, // $MISSING: ... looks more like the $ belongs to MISSING and not to the entire comment.

[smowton]

By all means make that a style requirement, but let's not produce confusing errors due to whitespace fussiness. At the very least we should produce an error that points concretely to the problem, rather than misreporting the MISSING expectation as a regular one as at present