Remove freed InvalidDomains from InvalidDomainMap.

Remove freed InvalidDomains from InvalidDomainMap.

Summary:
Since r306667, propagateInvalidStmtDomains gets a reference to an
InvalidDomainMap. As part of the branch leading to return false, the respective
domain is freed. It is, however, not removed from the InvalidDomainMap, leaking
a pointer to a freed object which results in a use-after-free. Fix this be
removing the domain from the map before returning.

We tried to derive a test case that reliably failes, but did not succeed in
producing one. Hence, for now the failures in our LNT bots must be sufficient
to keep this issue tested.

Reviewers: grosser, Meinersbur, bollu

Subscribers: bollu, nandini12396, pollydev, llvm-commits

Differential Revision: https://reviews.llvm.org/D34971

llvm-svn: 307499