Add ArrayDataTraits<> specialization for Array_Data<T>*.

Add ArrayDataTraits<> specialization for Array_Data<T>*.

Currently, we use wrong storage type for nested arrays. For example, the storage
type of the outer array of int8[][] is
StructPointer<Array_Data<int8_t>>. After this CL it will be
ArrayPointer<int8_t>.

The current code works because StructPointer happens to be of the same
size as ArrayPointer.

(The newly-added tests pass with/without this CL. But I think it is good
to have them.)

BUG=None
TEST=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=278356

[yzshen1, 2014-06-18 22:48:02]

Hi, Darin.

Would you please take a look? Thanks!

[darin (slow to review), 2014-06-19 05:44:01]

LGTM

Good catch!

[yzshen1, 2014-06-19 05:51:25]

The CQ bit was checked by yzshen@chromium.org

[commit-bot: I haz the power, 2014-06-19 05:54:05]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/yzshen@chromium.org/340223002/20001

[commit-bot: I haz the power, 2014-06-19 13:34:21]

Change committed as 278356