ObjectiveC migrator: tighten rule about when to
migrate to @property with getter name starting with
'is'.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188013 91177308-0d34-0410-b5e6-96231b3b80d8
unbreak buildbot on Windows.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188018 91177308-0d34-0410-b5e6-96231b3b80d8