[PSA] Fluent can now be used to localize UA Widgets

Hi all, Thanks to the work of James Teh [:Jamie] in bug 1659625, you can now use Fluent to localize UA Widgets. You'll need to create a custom `DOMLocalization` or `Localization` instance, and use `connectRoot` and `disconnectRoot` to integrate it into the UA Widget's lifecycle. An example of su

Intent to ship: selectionchange for input/textarea

Summary: selectionchange for text controls has been behind the flag `dom.select_events.textcontrols.enabled`, while the behaviour was different from Chrome’s as the events fired at each element instead of `document`. I intend to modify the behaviour to make the events fire at `document` and thus fo

Intent to prototype: ETP strict mode shims for content-blocked resources

Summary: ETP strict mode performs content-blocking, which can cause breakage on many sites ranging from features like Facebook's federated logins not working, to sites not being able to load at all. This currently occurs in private browsing mode, and/or if the user has enabled the option in Firef