- These operations are identical for Float32x4 and Int32x4.
- Make them generic, following the naming for generic Simd128 / S128
opcodes.
- F32x4/I32x4 -> S32x4, similarly to S128
- Float32x4/Int32x4 -> Simd32x4, similarly to Simd128.

LOG=N
BUG=v8:4124

Review-Url: https://codereview.chromium.org/2543773002
Cr-Commit-Position: refs/heads/master@{#41437}