Lower vector floating point arithmetic operations.

This adds lowering code for fadd, fsub, fmul, fdiv, and frem. frem, having no native x86 counterpart, is implemented by making a helper call.

BUG=none
R=jvoung@chromium.org, stichnot@chromium.org

Review URL: https://codereview.chromium.org/389653002
5 files changed