LibWeb: Add shadows to inline text

[darcusmao]

Hello, we are students at the University of Utah working on fixing a bug for Professor Panchekha's Web Browser class. We have implemented shadows for inline text as described in the issue #23214. To do this, we used similar code to that used in PaintableWithLines::paint(). The below image shows the inline text before the fix

This image is what LadyBird looks like after the fix.

[BuggieBot]

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[ADKaster]

Thanks for fixing this! A couple comments:

• Can you add one of the reproducers from the issue as a test? A Layout test seems appropriate, given the last example Sam posted. The test should fail without your changes applied, and pass with them.

• Please fixup-squash your commits and force-push one single commit that has the feature (and its test!) with a detailed commit description. Have a look at this video if you're not sure how to do that. https://youtu.be/ElRzTuYln0M

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions!

[stale]

This pull request has been closed because it has not had recent activity. Feel free to re-open if you wish to still contribute these changes. Thank you for your contributions!