Resolve URL/target reference at a single point in SVGUseElement

Resolve URL/target reference at a single point in SVGUseElement

The <base> URL can change between the attribute (href) is updated and
the shadow tree constructed. This causes confusion in the target
resolving code since it can produce different results at different
points in time.
Only resolve the URL on changes (to 'href'), extract the fragment
identifier and store whether the reference is local or not.
Refactor the SVGUseElement target element lookup with an eye to
future handling of "fragment-only" (local) URLs.
This makes the externalDocument in
SVGURIReference::targetElementFromIRIString unused, so remove that
codepath and simplify the function accordingly.

This changes behavior from resolving the URL and target element when
needed (depending on when layouts happen), to only when the 'href' is
mutated. This new behavior matches Edge, but not Gecko.

BUG=601203, 470608
Committed: https://crrev.com/91e189ad391cd78854f71f816c08c08e7bc991a4
Cr-Commit-Position: refs/heads/master@{#407128}

[fs, 2016-07-21 17:30:25]

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

[commit-bot: I haz the power, 2016-07-21 17:30:50]

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

[fs, 2016-07-21 18:48:42]

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

[commit-bot: I haz the power, 2016-07-21 18:48:45]

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

[fs, 2016-07-21 19:59:50]

fs@opera.com changed reviewers:
+ pdr@chromium.org, schenney@chromium.org

[fs, 2016-07-21 19:59:50]

I'll fix this ASSERT issue, he said. It'll be easy, he said.

[commit-bot: I haz the power, 2016-07-21 20:50:22]

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

[commit-bot: I haz the power, 2016-07-21 20:50:23]

Dry run: Try jobs failed on following builders:
  linux_chromium_asan_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[pdr., 2016-07-22 01:41:53]

Nice! LGTM

https://codereview.chromium.org/2173453002/diff/20001/third_party/WebKit/Layo...
File
third_party/WebKit/LayoutTests/svg/custom/use-external-base-change-assert.html
(right):

https://codereview.chromium.org/2173453002/diff/20001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/svg/custom/use-external-base-change-assert.html:4:
<script>
Nit: Can you move the script out of the use? I checked that it still crashes
without the patch.

https://codereview.chromium.org/2173453002/diff/20001/third_party/WebKit/Layo...
File
third_party/WebKit/LayoutTests/svg/custom/use-external-dynamic-base-change.html
(right):

https://codereview.chromium.org/2173453002/diff/20001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/svg/custom/use-external-dynamic-base-change.html:4:
<rect id="rect" width="200" height="100"/>
Nit: can you make this go from width=0 to width=100?

[fs, 2016-07-22 08:57:36]

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

[commit-bot: I haz the power, 2016-07-22 08:57:45]

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

[fs, 2016-07-22 10:29:21]

The CQ bit was checked by fs@opera.com

[fs, 2016-07-22 10:29:21]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org
Link to the patchset: https://codereview.chromium.org/2173453002/#ps40001
(title: "Test touchups")

[commit-bot: I haz the power, 2016-07-22 10:29:31]

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, 2016-07-22 10:56:14]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-07-22 10:58:33]

Description was changed from

==========
Resolve URL/target reference at a single point in SVGUseElement

The <base> URL can change between the attribute (href) is updated and
the shadow tree constructed. This causes confusion in the target
resolving code since it can produce different results at different
points in time.
Only resolve the URL on changes (to 'href'), extract the fragment
identifier and store whether the reference is local or not.
Refactor the SVGUseElement target element lookup with an eye to
future handling of "fragment-only" (local) URLs.
This makes the externalDocument in
SVGURIReference::targetElementFromIRIString unused, so remove that
codepath and simplify the function accordingly.

This changes behavior from resolving the URL and target element when
needed (depending on when layouts happen), to only when the 'href' is
mutated. This new behavior matches Edge, but not Gecko.

BUG=601203, 470608
==========

to

==========
Resolve URL/target reference at a single point in SVGUseElement

The <base> URL can change between the attribute (href) is updated and
the shadow tree constructed. This causes confusion in the target
resolving code since it can produce different results at different
points in time.
Only resolve the URL on changes (to 'href'), extract the fragment
identifier and store whether the reference is local or not.
Refactor the SVGUseElement target element lookup with an eye to
future handling of "fragment-only" (local) URLs.
This makes the externalDocument in
SVGURIReference::targetElementFromIRIString unused, so remove that
codepath and simplify the function accordingly.

This changes behavior from resolving the URL and target element when
needed (depending on when layouts happen), to only when the 'href' is
mutated. This new behavior matches Edge, but not Gecko.

BUG=601203, 470608

Committed: https://crrev.com/91e189ad391cd78854f71f816c08c08e7bc991a4
Cr-Commit-Position: refs/heads/master@{#407128}
==========

[commit-bot: I haz the power, 2016-07-22 10:58:34]

Patchset 3 (id:??) landed as
https://crrev.com/91e189ad391cd78854f71f816c08c08e7bc991a4
Cr-Commit-Position: refs/heads/master@{#407128}