[turbofan] Materialize the correct kind of constant for bit 1.

Bit 1 should be represented as Int32Constant 1 after simplified
lowering, but OneConstant returns NumberConstant 1.0.

R=jochen@chromium.org, hpayer@chromium.org

Review URL: https://codereview.chromium.org/820993002

Cr-Commit-Position: refs/heads/master@{#25919}