Before this commit, explicit extension receiver type check was performed
during found candidates analysis (together with arguments type check etc.)
Now we do it just after candidate is found, and filter the candidate
out if explicit receiver type is inappropriate.
This commit slightly changes resolve semantics,
replacing WRONG_RECEIVER with UNRESOLVED_REFERENCE in certain situations.
However, it provides significant performance boost.
Mikhail Glukhikh
374b59dee3