Check for styleResolver() in preparation for async style update.

Check for styleResolver() in preparation for async style update.

Currently, active stylesheets are appended to ScopedStyleResolver
through the StyleResolver. When we move to async stylesheet update with
ActiveStyleSheets being appended from StyleEngine, styleResolver() is
typically null the first time we update the active stylesheets.

Add a null check before accessing styleResolver() when adding
@font-face rules.

R=nainar@chromium.org,meade@chromium.org
BUG=567021
Committed: https://crrev.com/ff9f0b0877fcbe48fef3a32fc1c86cb706764b54
Cr-Commit-Position: refs/heads/master@{#434437}

[rune, 2016-11-24 23:30:51]

Description was changed from

==========
Check for styleResolver() in preparation for async style update.

Currently, active stylesheets are appended to ScopedStyleResolver
through the StyleResolver. When we move to async stylesheet update with
ActiveStyleSheets being appended from StyleEngine, styleResolver() is
typically null the first time we update the active stylesheets.

Add a null check before accessing styleResolver() when adding
@font-face rules.

R=nainar@chromium.org,meade@chromium.org
BUG=567021
TEST=
==========

to

==========
Check for styleResolver() in preparation for async style update.

Currently, active stylesheets are appended to ScopedStyleResolver
through the StyleResolver. When we move to async stylesheet update with
ActiveStyleSheets being appended from StyleEngine, styleResolver() is
typically null the first time we update the active stylesheets.

Add a null check before accessing styleResolver() when adding
@font-face rules.

R=nainar@chromium.org,meade@chromium.org
BUG=567021
==========

[rune, 2016-11-24 23:31:33]

The CQ bit was checked by rune@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2016-11-24 23:31:47]

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

[rune, 2016-11-24 23:35:49]

Applying the rest of my patches for 567021, it won't crash without this fix
because it's covered by ensureStyleResolver() in
HTMLDocumentParser::startBackgroundParser(). However, that call should probably
be replaced by updateViewport() in which case the styleResolver() might be null
here.

[meade_UTC10, 2016-11-25 00:39:08]

lgtm

[commit-bot: I haz the power, 2016-11-25 00:47:34]

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

[commit-bot: I haz the power, 2016-11-25 00:47:35]

Dry run: This issue passed the CQ dry run.

[rune, 2016-11-25 05:38:16]

The CQ bit was checked by rune@opera.com

[commit-bot: I haz the power, 2016-11-25 05:38:24]

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, 2016-11-25 05:41:38]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1480052296500960, "parent_rev":
"c6129bdb7bed57342dca89f75e3a0ff28892530c", "commit_rev":
"f7aecbb9c1bf98bec6393913cde3dfdbd5620cc0"}

[commit-bot: I haz the power, 2016-11-25 05:42:02]

Description was changed from

==========
Check for styleResolver() in preparation for async style update.

Currently, active stylesheets are appended to ScopedStyleResolver
through the StyleResolver. When we move to async stylesheet update with
ActiveStyleSheets being appended from StyleEngine, styleResolver() is
typically null the first time we update the active stylesheets.

Add a null check before accessing styleResolver() when adding
@font-face rules.

R=nainar@chromium.org,meade@chromium.org
BUG=567021
==========

to

==========
Check for styleResolver() in preparation for async style update.

Currently, active stylesheets are appended to ScopedStyleResolver
through the StyleResolver. When we move to async stylesheet update with
ActiveStyleSheets being appended from StyleEngine, styleResolver() is
typically null the first time we update the active stylesheets.

Add a null check before accessing styleResolver() when adding
@font-face rules.

R=nainar@chromium.org,meade@chromium.org
BUG=567021
==========

[commit-bot: I haz the power, 2016-11-25 05:42:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-25 05:43:33]

Description was changed from

==========
Check for styleResolver() in preparation for async style update.

Currently, active stylesheets are appended to ScopedStyleResolver
through the StyleResolver. When we move to async stylesheet update with
ActiveStyleSheets being appended from StyleEngine, styleResolver() is
typically null the first time we update the active stylesheets.

Add a null check before accessing styleResolver() when adding
@font-face rules.

R=nainar@chromium.org,meade@chromium.org
BUG=567021
==========

to

==========
Check for styleResolver() in preparation for async style update.

Currently, active stylesheets are appended to ScopedStyleResolver
through the StyleResolver. When we move to async stylesheet update with
ActiveStyleSheets being appended from StyleEngine, styleResolver() is
typically null the first time we update the active stylesheets.

Add a null check before accessing styleResolver() when adding
@font-face rules.

R=nainar@chromium.org,meade@chromium.org
BUG=567021

Committed: https://crrev.com/ff9f0b0877fcbe48fef3a32fc1c86cb706764b54
Cr-Commit-Position: refs/heads/master@{#434437}
==========

[commit-bot: I haz the power, 2016-11-25 05:43:34]

Patchset 1 (id:??) landed as
https://crrev.com/ff9f0b0877fcbe48fef3a32fc1c86cb706764b54
Cr-Commit-Position: refs/heads/master@{#434437}