Fix assertion when trying to set custom properties as named properties

Fix assertion when trying to set custom properties as named properties

This patch fixes a bug where trying to access a custom property as a
named property causes an assertion (e.g. e.style['--foo'] = 'a').
None of the named-property handling code on CSSStyleDeclaration should
support custom properties (we should actually use attributes instead of
named properties, crbug.com/628785, but that's another issue).

The added test already passes in Firefox.

BUG=643194
Committed: https://crrev.com/0dcfd301c47f8510004c295f14f348fd601e2c4e
Cr-Commit-Position: refs/heads/master@{#416502}

[Timothy Loh, 2016-09-05 04:42:20]

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

[commit-bot: I haz the power, 2016-09-05 04:42:24]

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

[Timothy Loh, 2016-09-05 04:42:56]

Description was changed from

==========
Fix assertion when trying to set custom properties as named properties

This patch fixes a bug where trying to access a custom property as a
named property causes an assertion (e.g. e.style['--foo'] = 'a').
None of the named-property handling code on CSSStyleDeclaration should
support custom properties (we should actually use attributes instead of
named properties, crbug.com/628785, but that's another issue).

BUG=643194
==========

to

==========
Fix assertion when trying to set custom properties as named properties

This patch fixes a bug where trying to access a custom property as a
named property causes an assertion (e.g. e.style['--foo'] = 'a').
None of the named-property handling code on CSSStyleDeclaration should
support custom properties (we should actually use attributes instead of
named properties, crbug.com/628785, but that's another issue).

The added test already passes in Firefox.

BUG=643194
==========

[Timothy Loh, 2016-09-05 04:42:57]

timloh@chromium.org changed reviewers:
+ meade@chromium.org, nainar@chromium.org

[Timothy Loh, 2016-09-05 04:43:46]

Forgot that named properties could also be set by o['name'] and not just o.name
in the patch that introduced this bug
(https://codereview.chromium.org/2288633002).

[nainar, 2016-09-05 04:46:01]

lgtm

[haraken, 2016-09-05 04:46:28]

LGTM

Let's land this asap since it's causing a P0 bug (crbug.com/642821). I'll mark
it as a duplicate of crbug.com/643194.

[meade_UTC10, 2016-09-05 04:51:25]

lgtm

[Timothy Loh, 2016-09-05 04:52:31]

The CQ bit was unchecked by timloh@chromium.org

[Timothy Loh, 2016-09-05 04:52:33]

The CQ bit was checked by timloh@chromium.org

[commit-bot: I haz the power, 2016-09-05 04:52:44]

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, 2016-09-05 06:06:33]

Description was changed from

==========
Fix assertion when trying to set custom properties as named properties

This patch fixes a bug where trying to access a custom property as a
named property causes an assertion (e.g. e.style['--foo'] = 'a').
None of the named-property handling code on CSSStyleDeclaration should
support custom properties (we should actually use attributes instead of
named properties, crbug.com/628785, but that's another issue).

The added test already passes in Firefox.

BUG=643194
==========

to

==========
Fix assertion when trying to set custom properties as named properties

This patch fixes a bug where trying to access a custom property as a
named property causes an assertion (e.g. e.style['--foo'] = 'a').
None of the named-property handling code on CSSStyleDeclaration should
support custom properties (we should actually use attributes instead of
named properties, crbug.com/628785, but that's another issue).

The added test already passes in Firefox.

BUG=643194
==========

[commit-bot: I haz the power, 2016-09-05 06:06:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-09-05 06:07:59]

Description was changed from

==========
Fix assertion when trying to set custom properties as named properties

This patch fixes a bug where trying to access a custom property as a
named property causes an assertion (e.g. e.style['--foo'] = 'a').
None of the named-property handling code on CSSStyleDeclaration should
support custom properties (we should actually use attributes instead of
named properties, crbug.com/628785, but that's another issue).

The added test already passes in Firefox.

BUG=643194
==========

to

==========
Fix assertion when trying to set custom properties as named properties

This patch fixes a bug where trying to access a custom property as a
named property causes an assertion (e.g. e.style['--foo'] = 'a').
None of the named-property handling code on CSSStyleDeclaration should
support custom properties (we should actually use attributes instead of
named properties, crbug.com/628785, but that's another issue).

The added test already passes in Firefox.

BUG=643194

Committed: https://crrev.com/0dcfd301c47f8510004c295f14f348fd601e2c4e
Cr-Commit-Position: refs/heads/master@{#416502}
==========

[commit-bot: I haz the power, 2016-09-05 06:07:59]

Patchset 1 (id:??) landed as
https://crrev.com/0dcfd301c47f8510004c295f14f348fd601e2c4e
Cr-Commit-Position: refs/heads/master@{#416502}