Run both iPhone and iPad simulator tests on iOS bots

Run both iPhone and iPad simulator tests on iOS bots

This matches downstream, where we build a universal binary, and then run tests on the 64-bit iPhone 5s simulator and the 32-bit iPad Retina simulator.

BUG=490189
Committed: https://crrev.com/1a640b7c4d502b1c7894274cfd9bfbb6f7f23fbd
Cr-Commit-Position: refs/heads/master@{#330915}

[smut, 2015-05-20 19:51:57]

smut@google.com changed reviewers:
+ sdefresne@chromium.org

[sdefresne, 2015-05-21 07:51:04]

The CQ bit was checked by sdefresne@chromium.org

[sdefresne, 2015-05-21 07:51:05]

lgtm

[commit-bot: I haz the power, 2015-05-21 07:51:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1150753002/1

[commit-bot: I haz the power, 2015-05-21 08:10:51]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-21 08:11:38]

Patchset 1 (id:??) landed as
https://crrev.com/1a640b7c4d502b1c7894274cfd9bfbb6f7f23fbd
Cr-Commit-Position: refs/heads/master@{#330915}