Make isNamelessStruct a member of TType This will be needed outside of InitializeVariables when removing unreferenced variables is added. Named struct type declarations cannot be pruned as easily as they might be referenced later. BUG=angleproject:2166 TEST=angle_unittests Change-Id: If1462abe67e62ae19bde97de3c8f3d15e99ae9ea Reviewed-on: https://chromium-review.googlesource.com/771790 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>