commit 734490ac5714ccd13b30d7fa2544eaad40580da6
author Dan Clark <daniec@microsoft.com> Tue Jun 22 00:29:53 2021
committer Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> Tue Jun 22 00:52:28 2021
tree e1e8dbaa7c1c560d8113e5aa89398dd049ebddba
parent d41f24fb67a2d65c9ae2d72f800b423a76f8d7ca

Pass the correct sourceURLs to DevTools for constructed stylesheets

A CSSStyleSheet imported as a CSS module script has the constructed
flag set
(https://wicg.github.io/construct-stylesheets/#cssstylesheet-constructed-flag).
This is because it is useful to treat imported CSSStyleSheets the same
way as stylesheets created via `new`. For example we want to be able
to add both to document.adoptedStyleSheets, and we want both to treat
@import rules the same way.

However, we want DevTools to display them differently. Sheets
created with `new` don't have a source file to show, but imported
sheets do, so we want the latter to be shown more like "normal"
stylesheets.

To enable DevTools to tell these types of constructed stylesheets apart,
start passing an empty sourceURL to DevTools for constructed stylesheets
created by `new`. The corresponding frontend change
https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2964580
will check for an empty sourceURL to determine whether to try to link
the stylesheet to a source file or not.

Additionally, a CSSStyleSheet for a module import now stores the
URL of the module request as its base URL. This is later passed to
DevTools as the source URL of the stylesheet. This works because the
base URL and source URL for a CSS module script are always the same.

This also happens to fix a bug with resolution of relative URLs in
CSS modules. The previous behavior was to resolve these using the URL
of the importing document. The new, correct, behavior is to resolve
them using the URL of the stylesheet resource.

Bug: 1219441
Change-Id: I48de349e1f7c8e10a329bff016cef68ac9901bb6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2964539
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Dan Clark <daniec@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#894456}