Clean up empty namespace handling and fix empty namespaces in compound selectors

Clean up empty namespace handling and fix empty namespaces in compound selectors

This patch makes our namespace handling code in selector parsing to use
emptyAtom to represent empty namespaces and nullAtom to represent no
namespace (e.g. "|a" vs. "a"), instead of having both as nullAtom and
a separate hasNamespace bool. This fixes a bug where we would interpret
in prependTypeSelectorIfNeeded an empty namespace as no namespace (i.e.
the default namespace).

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201755

[Timothy Loh, 2015-09-03 07:23:06]

timloh@chromium.org changed reviewers:
+ alancutter@chromium.org, ramya.v@samsung.com

[Timothy Loh, 2015-09-03 07:23:06]

This depends on https://codereview.chromium.org/1322543004... also probably no
one ever uses empty namespaces or will notice this :/

[alancutter (OOO until 2018), 2015-09-03 07:43:23]

lgtm with int.

https://codereview.chromium.org/1305973007/diff/20001/LayoutTests/fast/css/na...
File LayoutTests/fast/css/namespaces/empty-namespace-compound-selector-1.xhtml
(right):

https://codereview.chromium.org/1305973007/diff/20001/LayoutTests/fast/css/na...
LayoutTests/fast/css/namespaces/empty-namespace-compound-selector-1.xhtml:16: <Y
id="div" xmlns=""></Y>
Tagname "div" with id "target" would be less confusing here.

[Timothy Loh, 2015-09-03 08:35:05]

I fixed up a couple more things:
- Updated tests which expected '|a' to serialize as 'a'
- Don't break empty namespaces in querySelector

[alancutter (OOO until 2018), 2015-09-03 08:40:48]

lgtm

[Timothy Loh, 2015-09-03 09:11:28]

The CQ bit was checked by timloh@chromium.org

[commit-bot: I haz the power, 2015-09-03 09:11:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1305973007/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1305973007/60001

[commit-bot: I haz the power, 2015-09-03 09:16:37]

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

[commit-bot: I haz the power, 2015-09-03 09:16:38]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Timothy Loh, 2015-09-03 09:24:20]

The CQ bit was checked by timloh@chromium.org

[commit-bot: I haz the power, 2015-09-03 09:24:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1305973007/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1305973007/60001

[commit-bot: I haz the power, 2015-09-03 09:29:13]

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

[commit-bot: I haz the power, 2015-09-03 09:29:14]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Timothy Loh, 2015-09-04 00:45:47]

The CQ bit was checked by timloh@chromium.org

[commit-bot: I haz the power, 2015-09-04 00:46:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1305973007/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1305973007/60001

[commit-bot: I haz the power, 2015-09-04 00:50:50]

Committed patchset #4 (id:60001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201755