Port 93f05b64

Original Commit Message:

    They have the same lifetime. It's a match!

    Both structures are native context dependent and dealt with (creation,
    clearing, gathering feedback) at the same time. By treating the spaces used
    for literal boilerplates as feedback vector slots, we no longer have to keep
    track of the materialized literal count elsewhere.

    A follow-on CL removes even more parser infrastructure related to this count.

R=mvstanton@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=v8:5456
LOG=N

Review-Url: https://codereview.chromium.org/2659413002
Cr-Commit-Position: refs/heads/master@{#42778}