Use Object.observe() instead of Polyfills

Use Object.observe() instead of Polyfills

This is a clean up CL and should not change any behavior.

BUG=none
TEST=browsertest passes

Committed: https://crrev.com/5d73807f1fea63c692efe744b60365c29884ea0a
Cr-Commit-Position: refs/heads/master@{#319602}

[yoshiki, 2015-03-06 08:40:20]

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

[yoshiki, 2015-03-06 08:45:54]

@fukino-san, PTAL. Thanks.

[fukino, 2015-03-06 12:14:21]

lgtm with a nit.

https://codereview.chromium.org/984593002/diff/40001/ui/file_manager/audio_pl...
File ui/file_manager/audio_player/elements/track_list.js (right):

https://codereview.chromium.org/984593002/diff/40001/ui/file_manager/audio_pl...
ui/file_manager/audio_player/elements/track_list.js:136: * @param
{Array.<Object>} splices The detail of the change.
nit: splices -> changes in annotation

[fukino, 2015-03-06 12:14:23]

lgtm with a nit.

[yoshiki, 2015-03-09 07:47:34]

The CQ bit was checked by yoshiki@chromium.org

[yoshiki, 2015-03-09 07:47:34]

The patchset sent to the CQ was uploaded after l-g-t-m from fukino@chromium.org
Link to the patchset: https://codereview.chromium.org/984593002/#ps60001 (title:
"Fix the wrong comment.")

[yoshiki, 2015-03-09 07:47:52]

Thank you for reviewing!

[commit-bot: I haz the power, 2015-03-09 07:47:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/984593002/60001

[commit-bot: I haz the power, 2015-03-09 08:10:02]

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

[commit-bot: I haz the power, 2015-03-09 08:10:02]

Failed to apply the patch.

[commit-bot: I haz the power, 2015-03-09 08:10:06]

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

[yoshiki, 2015-03-09 08:40:57]

The CQ bit was checked by yoshiki@chromium.org

[yoshiki, 2015-03-09 08:40:58]

The patchset sent to the CQ was uploaded after l-g-t-m from fukino@chromium.org
Link to the patchset: https://codereview.chromium.org/984593002/#ps80001 (title:
"Rebase")

[commit-bot: I haz the power, 2015-03-09 08:41:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/984593002/80001

[commit-bot: I haz the power, 2015-03-09 09:10:03]

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

[commit-bot: I haz the power, 2015-03-09 09:10:05]

Failed to apply the patch.

[commit-bot: I haz the power, 2015-03-09 09:10:09]

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

[yoshiki, 2015-03-09 09:32:52]

Patchset #6 (id:100001) has been deleted

[yoshiki, 2015-03-09 09:34:56]

The CQ bit was checked by yoshiki@chromium.org

[yoshiki, 2015-03-09 09:34:57]

The patchset sent to the CQ was uploaded after l-g-t-m from fukino@chromium.org
Link to the patchset: https://codereview.chromium.org/984593002/#ps80001 (title:
"Rebase")

[commit-bot: I haz the power, 2015-03-09 09:35:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/984593002/80001

[commit-bot: I haz the power, 2015-03-09 09:35:56]

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

[commit-bot: I haz the power, 2015-03-09 09:35:57]

Failed to apply the patch.

[commit-bot: I haz the power, 2015-03-09 09:36:06]

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

[yoshiki, 2015-03-09 12:04:33]

The CQ bit was checked by yoshiki@chromium.org

[commit-bot: I haz the power, 2015-03-09 12:05:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/984593002/80001

[commit-bot: I haz the power, 2015-03-09 12:05:51]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2015-03-09 12:06:47]

Patchset 5 (id:??) landed as
https://crrev.com/5d73807f1fea63c692efe744b60365c29884ea0a
Cr-Commit-Position: refs/heads/master@{#319602}