Move CSS mask-image from inline data: to files

[daniel-beck]

Once done with them all, we'll be able to disallow data: images sources in Content-Security-Policy. See #23863 for more context.

This migrates images from inline data: to files. I kept them unchanged, just fixing up percent-encoded HTML entities.

Without the change to webpack.config.js the build would fail.

Testing done

Changed the CSP plugin config to disallow data: as img-src, enforced it, and clicked around on the UI. No findings were reported. Screenshots indicate it works:

Setup wizard:

Proposed changelog entries

• Migrate CSS mask-image attribute values from inline data: to files for better compatibility with restrictive Content-Security-Policy settings.

Proposed changelog category

/label internal,web-ui

Proposed upgrade guidelines

N/A

Submitter checklist

• The Jira issue, if it exists, is well-described.
• The changelog entries and upgrade guidelines are appropriate for the audience affected by the change (users or developers, depending on the change) and are in the imperative mood (see examples). Fill in the Proposed upgrade guidelines section only if there are breaking changes or changes that may require extra steps from users during upgrade.
• There is automated testing or an explanation as to why this change has no tests.
• New public classes, fields, and methods are annotated with @Restricted or have @since TODO Javadocs, as appropriate.
• New deprecations are annotated with @Deprecated(since = "TODO") or @Deprecated(forRemoval = true, since = "TODO"), if applicable.
• New or substantially changed JavaScript is not defined inline and does not call eval to ease future introduction of Content Security Policy (CSP) directives (see documentation).
• For dependency updates, there are links to external changelogs and, if possible, full differentials.
• For new APIs and extension points, there is a link to at least one consumer.

Desired reviewers

@mention

Before the changes are marked as ready-for-merge:

Maintainer checklist

• There are at least two (2) approvals for the pull request and no outstanding requests for change.
• Conversations in the pull request are over, or it is explicit that a reviewer is not blocking the change.
• Changelog entries in the pull request title and/or Proposed changelog entries are accurate, human-readable, and in the imperative mood.
• Proper changelog labels are set so that the changelog can be generated automatically.
• If the change needs additional upgrade steps from users, the upgrade-guide-needed label is set and there is a Proposed upgrade guidelines section in the pull request title (see example).
• If it would make sense to backport the change to LTS, a Jira issue must exist, be a Bug or Improvement, and be labeled as lts-candidate to be considered (see query).

[timja]

LGTM

[timja]

/label ready-for-merge

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This PR is now ready for merge, after ~24 hours, we will merge it if there's no negative feedback.

Thanks!

significant changes since

[daniel-beck]

I had to amend this in 54d0522 so went ahead and did the setup wizard too (0006a71)

[janfaracik]

Not a blocker - but any thoughts on exposing Symbols through an API so we don't duplicate them?

[timja]

Not a blocker - but any thoughts on exposing Symbols through an API so we don't duplicate them?

It would be better definitely although this isn't making the status quo any worse than before and it makes it easier to understand where the duplication is for a refactor.

[timja]

/label ready-for-merge

---

This PR is now ready for merge, after ~24 hours, we will merge it if there's no negative feedback.

Thanks!