The new operator converts an int32 input to float32. If the input cannot
be represented exactly in float32, the value is rounded using the
round-ties-even rounding mode (the default rounding mode).

I provide implementations of the new operator for x64, ia32, arm, arm64,
mips, mips64, ppc, and ppc64.

R=titzer@chromium.org, v8-arm-ports@googlegroups.com, v8-mips-ports@googlegroups.com, v8-ppc-ports@googlegroups.com

Review URL: https://codereview.chromium.org/1589363002

Cr-Commit-Position: refs/heads/master@{#33347}