Fix js_to_cpp_unittest handling of null arrays.

Fix js_to_cpp_unittest handling of null arrays.

This test is still disabled pending resolution of some mojo message
validation issues, but this version sould be correct given a correct
message validator.

In other words, running this with --gtest_also_run_disabled_tests is
a good way to test a message validator.

BUG=366797
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=270834

[Tom Sepez, 2014-05-15 19:10:22]

Trung for OWNERS review.

[viettrungluu, 2014-05-15 19:15:30]

lgtm

[Tom Sepez, 2014-05-15 19:16:09]

The CQ bit was checked by tsepez@chromium.org

[commit-bot: I haz the power, 2014-05-15 19:20:07]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-15 19:20:07]

Commit queue rejected this change because it did not recognize the base URL.
Please commit your change manually.

[Tom Sepez, 2014-05-15 21:35:35]

The CQ bit was checked by tsepez@chromium.org

[commit-bot: I haz the power, 2014-05-15 21:35:59]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tsepez@chromium.org/284243002/1

[commit-bot: I haz the power, 2014-05-15 22:34:11]

Change committed as 270834