[strong] fix strong object exception messages

[strong] fix strong object exception messages

A mistake in a recent CL has messed up the error messages for strong object
semantics.

BUG=
LOG=N

Committed: https://crrev.com/ea2cb139d6064e2a692258cc62bf444cd9023bcd
Cr-Commit-Position: refs/heads/master@{#28741}

[conradw, 2015-06-01 20:06:29]

conradw@chromium.org changed reviewers:
+ arv@chromium.org, rossberg@chromium.org

[conradw, 2015-06-01 20:06:29]

PTAL

apologies for the spam, uploaded the wrong version

[arv (Not doing code reviews), 2015-06-01 20:18:51]

LGTM

[conradw, 2015-06-01 20:39:43]

The CQ bit was checked by conradw@chromium.org

[commit-bot: I haz the power, 2015-06-01 20:40:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1166433007/1

[commit-bot: I haz the power, 2015-06-01 22:43:56]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-01 22:44:13]

Patchset 1 (id:??) landed as
https://crrev.com/ea2cb139d6064e2a692258cc62bf444cd9023bcd
Cr-Commit-Position: refs/heads/master@{#28741}