Check documentElement conditions in parser* DOM mutation methods

Check documentElement conditions in parser* DOM mutation methods

The parser should never violate the tree constraints by doing
something like appending multiple documentElements. The spec
says we should just drop these elements on the floor.

BUG=492843, 492730
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196371

[esprehn, 2015-06-02 04:25:32]

esprehn@chromium.org changed reviewers:
+ adamk@chromium.org, kouhei@chromium.org

[kouhei (in TOK), 2015-06-02 04:51:22]

lgtm

[esprehn, 2015-06-02 05:07:47]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2015-06-02 05:08:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1163863005/1

[commit-bot: I haz the power, 2015-06-02 07:21:11]

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

[commit-bot: I haz the power, 2015-06-02 07:21:12]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/6...)

[esprehn, 2015-06-02 22:09:52]

Okay do you want to look again? I had mess with editing to make this actually
work.

[esprehn, 2015-06-03 02:55:56]

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

[esprehn, 2015-06-03 02:55:56]

The patchset sent to the CQ was uploaded after l-g-t-m from kouhei@chromium.org
Link to the patchset: https://codereview.chromium.org/1163863005/#ps40001
(title: "Add the test again.")

[commit-bot: I haz the power, 2015-06-03 02:56:31]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1163863005/40001

[commit-bot: I haz the power, 2015-06-03 03:55:51]

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

[commit-bot: I haz the power, 2015-06-03 03:55:53]

Dry run: This issue passed the CQ dry run.

[kouhei (in TOK), 2015-06-03 05:02:09]

lgtm

[esprehn, 2015-06-03 05:14:36]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2015-06-03 05:15:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1163863005/40001

[commit-bot: I haz the power, 2015-06-03 05:19:21]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196371