Allow using SelectorQuery fast paths in quirks mode and disconnected subtrees.

Allow using SelectorQuery fast paths in quirks mode and disconnected subtrees.

Previously there was a single global switch in the form of
SelectorQuery::CanUseFastQuery which controlled if we use any fast path
at all in querySelector. It was trying to enforce the rules for the
original id fast path though, and meant we were disabling all the other
fast paths (class, tagName) in quirks documents even though there's no
need to do that. It also meant we wouldn't use the id fast path inside
disconnected ShadowRoots.

This patch removes CanUseFastQuery() and replaces it with specific
checks for the id fast path, and stores the now static checks for the
other fast paths in a member variable use_slow_scan_.

This means shadowRoot or element.querySelector("#a") for an element in
a ShadowRoot is now O(1) even when the ShadowRoot is not connected to
the document. It also means we'll use the class and id fast paths in
quirks mode and also disconnected subtrees.

BUG=703900
Review-Url: https://codereview.chromium.org/2875673006
Cr-Commit-Position: refs/heads/master@{#471384}
Committed: https://chromium.googlesource.com/chromium/src/+/ad2bef1e6dd219c8b8e1fbe58b86a896550634c9

[esprehn, 2017-05-11 22:24:46]

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

[esprehn, 2017-05-11 22:26:17]

esprehn@chromium.org changed reviewers:
+ meade@chromium.org, rune@opera.com

[commit-bot: I haz the power, 2017-05-11 22:26:38]

Dry run: 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, 2017-05-12 00:56:23]

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

[commit-bot: I haz the power, 2017-05-12 00:56:24]

Dry run: Try jobs failed on following builders:
  win_chromium_x64_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[meade_UTC10, 2017-05-12 04:22:56]

lgtm

[esprehn, 2017-05-12 18:32:27]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2017-05-12 18:35:06]

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, 2017-05-12 18:45:16]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1494613947362360, "parent_rev":
"4e36c746c6c51486f9e57e47a946ee35918fd9f0", "commit_rev":
"ad2bef1e6dd219c8b8e1fbe58b86a896550634c9"}

[commit-bot: I haz the power, 2017-05-12 18:45:24]

Description was changed from

==========
Allow using SelectorQuery fast paths in quirks mode and disconnected subtrees.

Previously there was a single global switch in the form of
SelectorQuery::CanUseFastQuery which controlled if we use any fast path
at all in querySelector. It was trying to enforce the rules for the
original id fast path though, and meant we were disabling all the other
fast paths (class, tagName) in quirks documents even though there's no
need to do that. It also meant we wouldn't use the id fast path inside
disconnected ShadowRoots.

This patch removes CanUseFastQuery() and replaces it with specific
checks for the id fast path, and stores the now static checks for the
other fast paths in a member variable use_slow_scan_.

This means shadowRoot or element.querySelector("#a") for an element in
a ShadowRoot is now O(1) even when the ShadowRoot is not connected to
the document. It also means we'll use the class and id fast paths in
quirks mode and also disconnected subtrees.

BUG=703900
==========

to

==========
Allow using SelectorQuery fast paths in quirks mode and disconnected subtrees.

Previously there was a single global switch in the form of
SelectorQuery::CanUseFastQuery which controlled if we use any fast path
at all in querySelector. It was trying to enforce the rules for the
original id fast path though, and meant we were disabling all the other
fast paths (class, tagName) in quirks documents even though there's no
need to do that. It also meant we wouldn't use the id fast path inside
disconnected ShadowRoots.

This patch removes CanUseFastQuery() and replaces it with specific
checks for the id fast path, and stores the now static checks for the
other fast paths in a member variable use_slow_scan_.

This means shadowRoot or element.querySelector("#a") for an element in
a ShadowRoot is now O(1) even when the ShadowRoot is not connected to
the document. It also means we'll use the class and id fast paths in
quirks mode and also disconnected subtrees.

BUG=703900

Review-Url: https://codereview.chromium.org/2875673006
Cr-Commit-Position: refs/heads/master@{#471384}
Committed:
https://chromium.googlesource.com/chromium/src/+/ad2bef1e6dd219c8b8e1fbe58b86...
==========

[commit-bot: I haz the power, 2017-05-12 18:45:25]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/ad2bef1e6dd219c8b8e1fbe58b86...