convert more object functions to return maybes

convert more object functions to return maybes

R=svenpanne@chromium.org

BUG=v8:3929
LOG=y

Committed: https://crrev.com/6130b02524059069413c1fccce5695c2802019b8
Cr-Commit-Position: refs/heads/master@{#26952}

[dcarney, 2015-03-02 16:15:03]

dcarney@chromium.org changed reviewers:
+ svenpanne@chromium.org

[dcarney, 2015-03-02 16:15:35]

ptal

i'm ooto tomorrow, so if the cq is working, please punch the cq button.

[Sven Panne, 2015-03-03 07:10:47]

LGTM, although "auto" seems to be a bit overused, let's perhaps revisit this
later.

[Sven Panne, 2015-03-03 07:10:50]

The CQ bit was checked by svenpanne@chromium.org

[commit-bot: I haz the power, 2015-03-03 07:11:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/972623003/140001

[commit-bot: I haz the power, 2015-03-03 07:14:35]

Committed patchset #8 (id:140001)

[commit-bot: I haz the power, 2015-03-03 07:14:51]

Patchset 8 (id:??) landed as
https://crrev.com/6130b02524059069413c1fccce5695c2802019b8
Cr-Commit-Position: refs/heads/master@{#26952}