clang-format: Fix corner case in one-per-line formatting.

clang-format: Fix corner case in one-per-line formatting.

Before (example is JS, but also applies to C++):
  return [
    aaaa()
        .bbbbbbbb('A'),
    aaaa().bbbbbbbb('B'),
    aaaa().bbbbbbbb('C'),
  ];

After:
  return [
    aaaa().bbbbbbbb('A'),
    aaaa().bbbbbbbb('B'),
    aaaa().bbbbbbbb('C'),
  ];

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@257079 91177308-0d34-0410-b5e6-96231b3b80d8