Allow <use> inside author shadow roots

Allow <use> inside author shadow roots

This patch fixes a bug where <use> elements did not work in author shadow
trees due to a restriction that <use> trees are not expanded inside
shadow trees. This restriction was in place so that we don't nest <use>
shadow trees but instead expand nested <use> elements manually using
the top-level <use> element.

For example:
<defs>
__<use id="a">
____<rect>
__<use id="b" xlink:href="#a">
</defs>
<use id="c" xlink:href="#b">

When creating the "c" shadow tree, "b" is first added:
<use id="c">
__#user-agent-shadow-root
____<use id="b">

And then "b" is "expanded" (see: expandUseElementsInShadowTree):
<use id="c">
__#user-agent-shadow-root
____<g id="b">
______<use id="a">

Finally "a" is "expanded":
<use id="c">
__#user-agent-shadow-root
____<g id="b">
______<g id="a">
________<rect>

The checks preventing <use> tree expansion in shadow trees were
intended to prevent the nested <use> elements (or <symbol>) from
creating nested shadow roots--notice there is only one shadow root
in the above example.

This patch switches the isInShadowTree checks with isInUserAgentShadowTree
which will prevent <use> elements from cloning their targets when nested
inside another <use> shadow tree, but allow <use> elements with author
shadow roots.

BUG=356891
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=170614

[esprehn, 2014-03-29 08:23:32]

I don't know what you're trying to check for, but you don't need the loop.
You only need to look at the containing shadow root and check its type.

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[pdr., 2014-03-29 20:40:18]

On 2014/03/29 08:23:32, esprehn wrote:
> I don't know what you're trying to check for, but you don't need the loop.
> You only need to look at the containing shadow root and check its type.
> 
> To unsubscribe from this group and stop receiving emails from it, send an
email
> to mailto:blink-reviews+unsubscribe@chromium.org.

PTAL

I removed the shadow tree loop and updated the change description to make it a
little clearer what's going on. I also added a test of <title> in a shadow tree.

[pdr., 2014-04-01 03:19:33]

On 2014/03/29 20:40:18, pdr wrote:
> On 2014/03/29 08:23:32, esprehn wrote:
> > I don't know what you're trying to check for, but you don't need the loop.
> > You only need to look at the containing shadow root and check its type.
> > 
> > To unsubscribe from this group and stop receiving emails from it, send an
> email
> > to mailto:blink-reviews+unsubscribe@chromium.org.
> 
> PTAL
> 
> I removed the shadow tree loop and updated the change description to make it a
> little clearer what's going on. I also added a test of <title> in a shadow
tree.

Ping?

[esprehn, 2014-04-01 23:38:40]

lgtm

[commit-bot: I haz the power, 2014-04-01 23:38:47]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pdr@chromium.org/216463003/20001

[commit-bot: I haz the power, 2014-04-01 23:56:09]

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

[commit-bot: I haz the power, 2014-04-01 23:56:09]

Try jobs failed on following builders:
  tryserver.blink on linux_blink_rel

[pdr., 2014-04-02 00:04:29]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2014-04-02 00:04:38]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/pdr@chromium.org/216463003/20001

[commit-bot: I haz the power, 2014-04-02 00:39:14]

Change committed as 170614