Fold FormDataList::getEntry(index) into DOMFormData.

Fold FormDataList::getEntry(index) into DOMFormData.

Fold FormDataList::getEntry(index) into DOMFormData without creating
FormDataList::Entry.
 - Add Item::file() to share code between itemsToEntry() and
   DOMFormDataIterationSource::next().
 - Add Item::isString() and isFile() for compatibility with Entry.
 - Add DOMFormData::decode() to decode CStrings in Item.

This CL has no behavior changes.

BUG=528840
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201957

[tkent, 2015-09-09 05:26:53]

Patchset #1 (id:1) has been deleted

[tkent, 2015-09-09 06:07:30]

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

[tkent, 2015-09-09 06:07:30]

Keishi, would you review this please?

[keishi, 2015-09-09 06:56:27]

LGTM

[tkent, 2015-09-09 06:57:06]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2015-09-09 06:57:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1334513002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1334513002/20001

[commit-bot: I haz the power, 2015-09-09 07:02:03]

Committed patchset #1 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201957