Use DOMRefCell in script crate

[tetsuharuohzeki]

#3050

Altough LayoutDataRef is touched from layout, we don't use DOMRefCell in it becasuse
it's expected to manipulate in layout task.

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[tetsuharuohzeki]

I have not converted yet XMLHttpRequest, URLSearchParams, ServoHTMLParser, Page, ScriptTask, and TimerManager. I thought that it's might be very rare cases that they're touched from layout task, thus it's should be checked in code review process.

Should we use DOMRefCell in them for checking unsafe borrowing at all points?

[jdm]

@saneyuki I think we should. In the future I'd like to add a lint to disallow RefCell in the script crate.

[tetsuharuohzeki]

@jdm ok. I'll push their patches.

[tetsuharuohzeki]

After merge this, I'll open the pull request which introduce dynamic checking about borrowing.

[jdm]

Thanks!

[tetsuharuohzeki]

I feel the last bors build error is similar to the one which we encounter in #3742.

Perhaps the previous base commit might have some latent issues, so I rebased this changeset on a latest master now.

[jdm]

r+

[jdm]

@bors: retry

[jdm]

@bors: retry

[bors-servo]

saw approval from jdm
at tetsuharuohzeki@f1c840d

[bors-servo]

merging saneyuki/servo/cell = f1c840d into auto

[bors-servo]

saneyuki/servo/cell = f1c840d merged ok, testing candidate = 8cbc40a

[bors-servo]

some tests failed:
failure: http://build.servo.org/builders/mac/builds/406

[bors-servo]

saw approval from jdm
at tetsuharuohzeki@f1c840d

[bors-servo]

saw approval from jdm
at tetsuharuohzeki@f1c840d

[bors-servo]

merging saneyuki/servo/cell = f1c840d into auto

[bors-servo]

saneyuki/servo/cell = f1c840d merged ok, testing candidate = f5e8df9

[bors-servo]

all tests pass:
success: http://build.servo.org/builders/linux/builds/409
success: http://build.servo.org/builders/mac/builds/416

[bors-servo]

fast-forwarding master to auto = f5e8df9

[tetsuharuohzeki]

In this pull request, I replaced almost RefCell<T> to DOMRefCell<T>, but I didn't add to use DOMRefCell<T>.borrow_for_layout(). So it will use only parts of RefCell<T> embed in the new type, I think it will not cause any side effects...

[jdm]

Yes, I don't believe any of the members being changed should be in use by the layout task.

[tetsuharuohzeki]

Can only reviewers command to build to bors?

[jdm]

Yeah :/

[tetsuharuohzeki]

😢