Avoid unchecked casts in UA shadow DOM.

Avoid unchecked casts in UA shadow DOM.

If we have a way to leak UA shadow DOM to web authors or Chrome extension authors,
these unchecked casts would be dangerous.
This CL introduces toFooTypeOrDie() helpers, and apply it to UA shadow DOM.

BUG=668970
Committed: https://crrev.com/2ce7841faa0fcfb4bff02b808745a9399a1c0603
Cr-Commit-Position: refs/heads/master@{#434899}

[tkent, 2016-11-29 01:10:57]

The CQ bit was checked by tkent@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-11-29 01:11:47]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[tkent, 2016-11-29 01:48:24]

Description was changed from

==========
Avoid unchecked casts in UA shadow trees.

BUG=668970
==========

to

==========
Avoid unchecked casts in UA shadow DOM.

If we have a way to leak UA shadow DOM to web authors or Chrome extension
authors,
these unchecked casts would be dangerous.
This CL introduces toFooTypeOrDie() helpers, and apply it to UA shadow DOM.

BUG=668970
==========

[tkent, 2016-11-29 03:39:21]

tkent@chromium.org changed reviewers:
+ hayato@chromium.org, yosin@chromium.org

[tkent, 2016-11-29 03:39:22]

yosin@, or hayato@, would you review this please?

[commit-bot: I haz the power, 2016-11-29 04:04:37]

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

[commit-bot: I haz the power, 2016-11-29 04:04:37]

Dry run: This issue passed the CQ dry run.

[hayato, 2016-11-29 04:13:10]

lgtm

[tkent, 2016-11-29 05:06:49]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2016-11-29 05:07:10]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-11-29 05:10:47]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1480396009186130, "parent_rev":
"fdda0eb1809c108faccdc36b0f86ea0a37a045a4", "commit_rev":
"4b60955f487bc0077aa798fcba5e9ea69a4b6922"}

[commit-bot: I haz the power, 2016-11-29 05:12:16]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-29 05:16:12]

Description was changed from

==========
Avoid unchecked casts in UA shadow DOM.

If we have a way to leak UA shadow DOM to web authors or Chrome extension
authors,
these unchecked casts would be dangerous.
This CL introduces toFooTypeOrDie() helpers, and apply it to UA shadow DOM.

BUG=668970
==========

to

==========
Avoid unchecked casts in UA shadow DOM.

If we have a way to leak UA shadow DOM to web authors or Chrome extension
authors,
these unchecked casts would be dangerous.
This CL introduces toFooTypeOrDie() helpers, and apply it to UA shadow DOM.

BUG=668970

Committed: https://crrev.com/2ce7841faa0fcfb4bff02b808745a9399a1c0603
Cr-Commit-Position: refs/heads/master@{#434899}
==========

[commit-bot: I haz the power, 2016-11-29 05:16:14]

Patchset 1 (id:??) landed as
https://crrev.com/2ce7841faa0fcfb4bff02b808745a9399a1c0603
Cr-Commit-Position: refs/heads/master@{#434899}