As seen with Bug 1843604, the contexts created by browsingContext.create are sometimes returned before their content window has an actual size.

Some of our wdspec tests attempt to measure the window size using script.evaluate and read incorrect values.

We should ensure that the content window of the new contexts have a valid size so that consumers can check the window size without having to wait for some additional event or arbitrary delay.

This prevents intermittent failure where measuring the content window size right after creating a tab could return incorrect values.

Depends on D185312

https://hg.mozilla.org/mozilla-central/rev/918000df0800

beta is still affected and it might be good to get this patch uplifted.

Comment on attachment 9347196 [details]
Bug 1847044 - [bidi] Force a reflow on contexts created by browsingContext.create

Beta/Release Uplift Approval Request

• User impact if declined: fixes frequent intermittent failures
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): minor JS change in WebDriver BiDi implementation, no impact for regular users
• String changes made/needed:
• Is Android affected?: No

Comment on attachment 9347196 [details]
Bug 1847044 - [bidi] Force a reflow on contexts created by browsingContext.create

Approved for 117.0b4.