Sanitize inheritance in callers of utils.expose

Sanitize inheritance in callers of utils.expose

- Let all private classes inherit from the null prototype.
- Use safe built-ins.
- Minor drive-by fixes (code style).

BUG=603748, 591164
Review-Url: https://codereview.chromium.org/1915753002
Cr-Commit-Position: refs/heads/master@{#390510}
(cherry picked from commit 931719c51866a7c2e272114517cc52aa6581adff)

Committed: https://chromium.googlesource.com/chromium/src/+/c29bc7edad5f1e80cad11d50a1cd880456cb54cb

[robwu, 2016-05-02 20:27:52]

Description was changed from

==========
Sanitize inheritance in callers of utils.expose

- Let all private classes inherit from the null prototype.
- Use safe built-ins.
- Minor drive-by fixes (code style).

BUG=603748,591164

Review-Url: https://codereview.chromium.org/1915753002
Cr-Commit-Position: refs/heads/master@{#390510}
(cherry picked from commit 931719c51866a7c2e272114517cc52aa6581adff)
==========

to

==========
Sanitize inheritance in callers of utils.expose

- Let all private classes inherit from the null prototype.
- Use safe built-ins.
- Minor drive-by fixes (code style).

BUG=603748,591164

Review-Url: https://codereview.chromium.org/1915753002
Cr-Commit-Position: refs/heads/master@{#390510}
(cherry picked from commit 931719c51866a7c2e272114517cc52aa6581adff)

Committed:
https://chromium.googlesource.com/chromium/src/+/c29bc7edad5f1e80cad11d50a1cd...
==========

[robwu, 2016-05-02 20:27:54]

Committed patchset #1 (id:1) manually as
c29bc7edad5f1e80cad11d50a1cd880456cb54cb.