Fix flakiness of imported/web-platform-tests/html/syntax/parsing/html5lib_testsNN.html.

Fix flakiness of imported/web-platform-tests/html/syntax/parsing/html5lib_testsNN.html.

Root cause:
Our testharnessreport.js removes unnecessary text nodes in a callback registered
by add_completion_callback() [1]. The html5lib tests add other completion
callbacks to show failure reasons, and they run after the callback of
testharnessreport.js.  So, the failure reasons remain in *-expected.txt.

Resolution:
testharness.js doesn't provide a way to specify that "This callback must run at
the end of callbacks." So we delay the text nodes cleanup by setTimeout(done, 0).

[1] https://github.com/w3c/testharness.js/blob/master/docs/api.md#callback-api

BUG=527262
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201628

[tkent, 2015-09-02 06:46:54]

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

[tkent, 2015-09-02 06:46:54]

kojii@, can you review this?

[kojii, 2015-09-02 07:46:10]

lgtm

[tkent, 2015-09-02 07:47:30]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2015-09-02 07:47:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1303313006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1303313006/1

[commit-bot: I haz the power, 2015-09-02 08:04:34]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201628