Upgrade parser-created Custom Elements in creation order.

Upgrade parser-created Custom Elements in creation order.

Originally, parser-created Custom Elements were upgraded in reverse
order (which quickly and dirtily ensured that an element's children
were upgraded before the element itself.) Then we rethought this and
upgraded them post-order (which meant an element's children were still
upgraded before the element itself, but siblings were upgraded in
order.)

Now parser-created Custom Elements are upgraded in creation order (ie
pre-order.) This is consistent with how Custom Elements are upgraded
when cloning a subtree of nodes.

This is described here:
<https://www.w3.org/Bugs/Public/show_bug.cgi?id=23778>;

BUG=234509
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=162229

[dominicc (has gone to gerrit), 2013-11-15 07:14:50]

PTAL

[dominicc (has gone to gerrit), 2013-11-18 08:02:53]

morrita is under the weather... +dglazkov, -morrita.

[dglazkov, 2013-11-18 18:02:11]

lgtm

[commit-bot: I haz the power, 2013-11-18 18:02:32]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dominicc@chromium.org/69533003/60001

[commit-bot: I haz the power, 2013-11-18 20:24:54]

Change committed as 162229