Whitespace.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194680 91177308-0d34-0410-b5e6-96231b3b80d8
yaml::Input::mapTag(): Don't use StringRef to hold return type of std::string.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194681 91177308-0d34-0410-b5e6-96231b3b80d8