With Visual Studio 2015, the Traits type alias is not considered
within scope yet for the constructor's argument list. Instead Use
the template argument directly.

BUG=swiftshader:7

Change-Id: I677f5bed1a4749aba921a23ed5b1466431147069
Reviewed-on: https://chromium-review.googlesource.com/379915Reviewed-by: Jim Stichnoth <stichnot@chromium.org>
Tested-by: Nicolas Capens <nicolascapens@google.com>