Fix type errors in unit test utilities.

Fix type errors in unit test utilities.

Fixes all bad casts associated with operands of call and select operators
in the test suite.

Cleanup for cfi_vptr=1; see https://www.chromium.org/developers/testing/control-flow-integrity

BUG=chromium:457523
R=bmeurer@chromium.org
LOG=N

Committed: https://crrev.com/e70f23f9591998a803883de58d4b27311924624b
Cr-Commit-Position: refs/heads/master@{#30531}

[Benedikt Meurer, 2015-09-02 04:04:18]

lgtm

[pcc, 2015-09-02 04:30:14]

The CQ bit was checked by pcc@google.com

[commit-bot: I haz the power, 2015-09-02 04:30:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1329643002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1329643002/1

[commit-bot: I haz the power, 2015-09-02 04:55:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-02 04:55:37]

Patchset 1 (id:??) landed as
https://crrev.com/e70f23f9591998a803883de58d4b27311924624b
Cr-Commit-Position: refs/heads/master@{#30531}