Revert of [x86] Use better left operand heuristic for Float64Add and Float64Mul. (patchset #1 id:1 of https://codereview.chromium.org/958583003/)

Reason for revert:
Tanks on Atom and Haswell

Original issue's description:
> [x86] Use better left operand heuristic for Float64Add and Float64Mul.
>
> R=dcarney@chromium.org
>
> Committed: https://crrev.com/9da259fb1f4ecfefeb2cf7efbe449d8aa1904032
> Cr-Commit-Position: refs/heads/master@{#26849}

TBR=dcarney@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/972243002

Cr-Commit-Position: refs/heads/master@{#26973}