[turbofan] Run DeadCodeElimination as part of the generic lowering phase.

[turbofan] Run DeadCodeElimination as part of the generic lowering phase.

This way we don't need the separate late control reduction pass over the
graph, plus we can also reduce dead code recognized by generic lowering.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1198923002

Cr-Commit-Position: refs/heads/master@{#29174}