Rearrange the Document interfaces to match the many specs

Rearrange the Document interfaces to match the many specs

https://dom.spec.whatwg.org/#interface-document
https://html.spec.whatwg.org/#the-document-object
and many other specs with partial Document interfaces.

To make reviewing easier, this commit only changes the order of lines
and adds comments. Actual spec sync will be done separate.

The order of the generated code changes, but there are no actual
changes.

BUG=460722
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=190981

[philipj_slow, 2015-02-27 04:07:28]

philipj@opera.com changed reviewers:
+ haraken@chromium.org

[philipj_slow, 2015-02-27 04:07:29]

PTAL. Part 2 in https://codereview.chromium.org/960923005

[haraken, 2015-02-27 07:45:56]

LGTM, thanks for splitting!

[philipj_slow, 2015-02-27 07:58:51]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2015-02-27 07:59:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/961693004/1

[commit-bot: I haz the power, 2015-02-27 08:02:07]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=190981