Add type annotations to gallery/js/mosaic_mode.js.

Add type annotations to gallery/js/mosaic_mode.js.

BUG=433728
TEST=GYP_GENERATORS=ninja tools/gyp/gyp --depth . ui/file_manager/gallery/js/compiled_resources.gyp && ninja -C out/Default | grep "gallery/js/mosaic_mode.js"

Committed: https://crrev.com/fcdfa398723720472a27b0b3f279750838d22faa
Cr-Commit-Position: refs/heads/master@{#308320}

[yawano, 2014-12-15 05:28:24]

yawano@chromium.org changed reviewers:
+ fukino@chromium.org

[yawano, 2014-12-15 05:28:25]

PTAL. Thank you!

[yawano, 2014-12-15 05:33:16]

tileRect and imageRect of Mosaic.transform should have allowed null values.
Fixed it. PTAL. Thanks.

[fukino, 2014-12-15 05:41:23]

lgtm!

[yawano, 2014-12-15 05:41:53]

On 2014/12/15 05:41:23, fukino wrote:
> lgtm!

Thank you!

[yawano, 2014-12-15 05:41:55]

The CQ bit was checked by yawano@chromium.org

[commit-bot: I haz the power, 2014-12-15 05:42:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/805723003/20001

[commit-bot: I haz the power, 2014-12-15 06:34:56]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-12-15 06:35:39]

Patchset 2 (id:??) landed as
https://crrev.com/fcdfa398723720472a27b0b3f279750838d22faa
Cr-Commit-Position: refs/heads/master@{#308320}