Where possible:
- eliminate special-case code generation for simulator.
- eliminate #ifdefs.

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

Review URL: https://codereview.chromium.org/1607663004

Cr-Commit-Position: refs/heads/master@{#33407}