The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/146d766c73164c7cfe3fb28509512e92698bfa53

commit 146d766c73164c7cfe3fb28509512e92698bfa53
Author: Anders Hartvoll Ruud <andruud@chromium.org>
Date: Fri Jun 22 16:54:57 2018

Correctly resolve relative URLs for registered custom properties.

Relative URLs in registered custom properties must resolve against the
base URL of the originating stylesheet. For instance, consider a style-
sheet at /style/mystyle.css:

  --foo: url("myimage.jpg");

And a document at /index.html:

  <style>
    background-image: var(--foo);
  </style>

If the property --foo is registered with syntax <url>, then the background-
image should be /style/myimage.jpg.

This is contrary to non-registered properties, in which case the
background-image would be /myimage.jpg.

To implement this, this patch scans for URL tokens and 'url('-function
tokens after (var-)resolving the registered custom property
(see CSSVariableResolver::ResolveCustomProperty). The token containing
the relative URL is then rewritten (in-place) to contain an absolute URL
instead.

To avoid doing unnecessary work, we only scan the token stream if

CSSVariableData::needs_variable_resolution_ is set. This is set either
if needs_url_resolution_ is set (because var-references could produce
relative URLs), or if the token stream contains URL/function-tokens.
When a resolved CSSVariableData is created (::CreateResolved), it is
assumed that the incoming token stream contains no URLs that need to be
resolved.

R=futhark@chromium.org, timloh@chromium.org

Bug:  851490 
Change-Id: I25b1e839fc92eb538f30670fe91fc92a1ad9d5ea
Reviewed-on: https://chromium-review.googlesource.com/1109975
Commit-Queue: Anders Ruud <andruud@chromium.org>
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569663}
[add] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/WebKit/LayoutTests/external/wpt/css/css-properties-values-api/support/alt/alt.css
[add] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/WebKit/LayoutTests/external/wpt/css/css-properties-values-api/support/alt/alt.js
[add] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/WebKit/LayoutTests/external/wpt/css/css-properties-values-api/support/main/main.css
[add] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/WebKit/LayoutTests/external/wpt/css/css-properties-values-api/support/main/main.js
[add] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/WebKit/LayoutTests/external/wpt/css/css-properties-values-api/support/main/main.utf16be.css
[add] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/WebKit/LayoutTests/external/wpt/css/css-properties-values-api/url-resolution.tentative.html
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/animation/css_interpolation_type.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/css_syntax_descriptor.h
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/css_variable_data.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/css_variable_data.h
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/cssom/css_unparsed_value.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/cssom/style_value_factory.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/parser/css_parser_impl.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/parser/css_property_parser.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/parser/css_property_parser_helpers.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/parser/css_variable_parser.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/parser/css_variable_parser.h
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/property_registration.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/resolver/css_variable_resolver.cc
[modify] https://crrev.com/146d766c73164c7cfe3fb28509512e92698bfa53/third_party/blink/renderer/core/css/resolver/css_variable_resolver.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/31f4d3d2e73367ffde3dfa4184f446123ae35874

commit 31f4d3d2e73367ffde3dfa4184f446123ae35874
Author: Anders Hartvoll Ruud <andruud@chromium.org>
Date: Tue Jul 03 08:35:01 2018

[css-properties-values-api]: Drop .tentative from URL resolution test.

R=eae@chromium.org

Bug:  851490 
Change-Id: I0090986f81763d3c84f1245d5340286f9a3a1dff
Reviewed-on: https://chromium-review.googlesource.com/1121463
Reviewed-by: Emil A Eklund <eae@chromium.org>
Commit-Queue: Anders Ruud <andruud@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572145}
[rename] https://crrev.com/31f4d3d2e73367ffde3dfa4184f446123ae35874/third_party/WebKit/LayoutTests/external/wpt/css/css-properties-values-api/url-resolution.html