Move ColorChooser{,Client} and DateTimeChooser{,Client} from platform to core.

Move ColorChooser{,Client} and DateTimeChooser{,Client} from platform to core.

We're going to add |Element& ownerElement()| to ColorChooserClient
and DateTimeChooserClient, and add |AXObject* rootAXObject()| to
ColorChooser and DateTimeChooser.
Classes in platform/ can't refer to core classes such as Element and
AXObject. So we move these classes.

BUG=123896
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180934

[tkent, 2014-08-26 23:37:28]

Patchset #2 (id:20001) has been deleted

[tkent, 2014-08-26 23:38:53]

Patchset #1 (id:1) has been deleted

[tkent, 2014-08-27 00:08:10]

Patchset #1 (id:40001) has been deleted

[tkent, 2014-08-27 01:05:20]

tkent@chromium.org changed reviewers:
+ keishi@chromium.org

[tkent, 2014-08-27 01:05:20]

Please review this.

[keishi, 2014-08-27 04:17:40]

lgtm

[tkent, 2014-08-27 04:18:24]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2014-08-27 04:18:56]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tkent@chromium.org/512563002/60001

[commit-bot: I haz the power, 2014-08-27 04:23:36]

Committed patchset #1 (60001) as 180934