Work around a bug with MSVC 10 where it fails to recognize a valid use

of typename. GCC and Clang were fine with this, but MSVC won't accept
it. Fortunately, it also doesn't need it. Yuck.

Thanks to Nakamura for pointing this out in IRC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158593 91177308-0d34-0410-b5e6-96231b3b80d8