Execute print user script in page content world

[alistairjcbrown]

Task/Issue URL: Related to https://app.asana.com/0/1199230911884351/1200442572797700/f
Tech Design URL:
CC:

Description:

The print user script needs to execute in the page content world so that
it mutates the globals used by the page which the user is interacting
with. The existing setup runs scripts under the default content world
(which is what you generally want), but this script is a special case as
we want to overwrite a global function on the window object.

Steps to test this PR:

1. Go to https://printablefreecoloring.com/print/animals/coloring-alligator-414.jpg
   • This is actually a webpage which calls window.print()
2. Expect print dialog to appear

Testing checklist:

• Test with Release configuration

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Internal references:

Software Engineering Expectations
Technical Design Template
When ready for review, remember to post the PR in MM

[samsymons]

Unfortunately I don't have time to finish up this review before heading out for the rest of the week, unassigning myself for now. But, I do think we should add a contentWorld property to UserScript and let scripts override it directly. Any thoughts on this @tomasstrba @brindy?

[tomasstrba]

@alistairjcbrown, I'm sorry, but this is a bit harder to follow. Is the next step review or is additional work required?

[samsymons]

Checking in on this PR, I'd like to close it out this week. I have some BSK changes in mind that could help out with this, will see about implementing those during Quick Wins Days this week.

[alistairjcbrown]

@tomasstrba @samsymons

Is the next step review or is additional work required?

This PR works as expected, but to get there PrintingUserScript had to reimplement makeWKUserScript instead of getting it from BrowserServicesKit, and we now having (more) content world specific functions in WKUserContentControllerExtension.

I guess ideally this PR could have some review to see if the approach is suitable for now -- and weigh that against if we'd first want to, a) figure out a nicer way to make the chosen content world configurable and, b) then back port this approach to BrowserServicesKit.
My vote would be land this PR, figure out the above, and then update at the same time as bumping the BrowserServicesKit version used -- but I'm also not enough in the weeds to know the gotchas of that approach.

Edit: There may also be tests failing -- I have access to bitrise now, so I'll take a look once this CI run finishes

[samsymons]

@alistairjcbrown Finally taking a proper look at this, so sorry for the wait

EDIT: yet again F&F has foiled this, despite my best attempts

[alistairjcbrown]

@samsymons @jonathanKingston Updated to use requiresRunInPageContentWorld from BrowserServicesKit 👍

[alistairjcbrown]

@jonathanKingston @samsymons Updated for feedback -- the diff for this PR is looking pretty sweet! 😁

[samsymons]

@alistairjcbrown You weren't kidding, this is super clean. ✨ LGTM!

[jonathanKingston]

Thanks for cleaning up based on feedback! 💯