Remove empty constructor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188232 91177308-0d34-0410-b5e6-96231b3b80d8
Reflow comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188233 91177308-0d34-0410-b5e6-96231b3b80d8
Add comment and source to testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188234 91177308-0d34-0410-b5e6-96231b3b80d8