Port 89bb66de

Original commit message:
    Original CL: https://codereview.chromium.org/1375253002/

    Implement machine instruction scheduling after instruction selection.

R=baptiste.afsa@arm.com, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1534433004

Cr-Commit-Position: refs/heads/master@{#32918}