ozone: Handle default cursors with no bitmap in BitmapCursorFactoryOzone

ozone: Handle default cursors with no bitmap in BitmapCursorFactoryOzone

Looks like there's fewer bitmaps than cursor types. On CrOS X11 we
fallback to left pointer, so do the same here.

BUG=410870
TEST=manual on link_freon
NOTRY=true

Committed: https://crrev.com/b0f88f7c45564264315e410cb249f3a9b6bffe2a
Cr-Commit-Position: refs/heads/master@{#293333}

[spang, 2014-09-04 16:31:49]

spang@chromium.org changed reviewers:
+ alexst@chromium.org

[alexst (slow to review), 2014-09-04 17:24:02]

lgtm

[spang, 2014-09-04 20:53:12]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2014-09-04 20:55:36]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/spang@chromium.org/540103002/1

[commit-bot: I haz the power, 2014-09-04 20:58:03]

Committed patchset #1 (id:1) as 06fc1e0a3b7bd3807e4c7de8c42297fd7339724b

[commit-bot: I haz the power, 2014-09-10 03:32:35]

Patchset 1 (id:??) landed as
https://crrev.com/b0f88f7c45564264315e410cb249f3a9b6bffe2a
Cr-Commit-Position: refs/heads/master@{#293333}