Generated code performs distinct floating multiply and add/subtract
operations.  Tests fail when GCC uses fmadd/fmsub to calculate the
expected result since these instructions provide higher accuracy due
to the lack of an intermediate round.

R=machenbach@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1416123007

Cr-Commit-Position: refs/heads/master@{#31918}