Port 2e329666

Original commit message:
    ... instead of doing stack magic.  This is a cleanup in preparation for the new
    generators implementation.

R=neis@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, bjaideep@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1874323002

Cr-Commit-Position: refs/heads/master@{#35416}