- Adds Float32x4 ExtractLane, ReplaceLane, Splat, Add, Sub,
and conversions to Int32x4 and Uint32x4.
- Adds Int32x4 ExtractLane, ReplaceLane, Splat, Add, Sub and
conversions to Float32x4 (int and unsigned int).
- Adds Int32x4 CompareEqual, CompareNotEqual.
- Adds S32x4 Select.
- Adds tests for all new SIMD operations.

LOG=N
BUG=v8:4124

Review-Url: https://codereview.chromium.org/2584863002
Cr-Commit-Position: refs/heads/master@{#41828}