Ensure that privates are private.

Ensure that privates are private.

- Remove JS code injection functionality from UtilsNativeHandler.
- Ensure that utils.expose only exposes public properties.
- Prevent privates from getting poisoned via arbitrary constructor invocations.
- Prevent privates from leaking through prototypes.

BUG=603748
Review URL: https://codereview.chromium.org/1903303002

Cr-Commit-Position: refs/heads/master@{#389292}
(cherry picked from commit 77e0fbe12e32b16d5c1d7c0380b45fde363004b2)

Committed: https://chromium.googlesource.com/chromium/src/+/f2b970209b08639170042334a2f1f2342f8a9113

[robwu, 2016-05-02 20:24:16]

Description was changed from

==========
Ensure that privates are private.

- Remove JS code injection functionality from UtilsNativeHandler.
- Ensure that utils.expose only exposes public properties.
- Prevent privates from getting poisoned via arbitrary constructor invocations.
- Prevent privates from leaking through prototypes.

BUG=603748

Review URL: https://codereview.chromium.org/1903303002

Cr-Commit-Position: refs/heads/master@{#389292}
(cherry picked from commit 77e0fbe12e32b16d5c1d7c0380b45fde363004b2)
==========

to

==========
Ensure that privates are private.

- Remove JS code injection functionality from UtilsNativeHandler.
- Ensure that utils.expose only exposes public properties.
- Prevent privates from getting poisoned via arbitrary constructor invocations.
- Prevent privates from leaking through prototypes.

BUG=603748

Review URL: https://codereview.chromium.org/1903303002

Cr-Commit-Position: refs/heads/master@{#389292}
(cherry picked from commit 77e0fbe12e32b16d5c1d7c0380b45fde363004b2)

Committed:
https://chromium.googlesource.com/chromium/src/+/f2b970209b08639170042334a2f1...
==========

[robwu, 2016-05-02 20:24:18]

Committed patchset #1 (id:1) manually as
f2b970209b08639170042334a2f1f2342f8a9113.