Used by Puppeteer, Playwright, and parts of Gutenberg. Might be important to have.

We will run Guteberg tests soon with all the upcoming improvements over the nexts, and will re-prioritize if necessary.

As given by Joel this is used all over the place in Playwright to attach a script via Page.addScriptToEvaluateOnNewDocument as soon as possible. Here a short description as it should behave:

Controls whether to automatically attach to new targets which are considered to be related to this one. When turned on, attaches to all existing related targets as well. When turned off, automatically detaches from all currently attached targets

To prevent race conditions on the page, we should get this implemented.