This pull request to adds better support for OOP iframes (see #2548)
The current problem with OOP iframes is that they are moved to a different target. Because of this, the previous versions of Puppeteer pretty much ignored them.
This change extends the FrameManager to already take OOP iframes into account and hides the fact that those frames are actually in different targets.
Further work needs to be done to also make the NetworkManager aware of these and to make sure that settings like emulations etc. are also properly passed down to the new targets.
* chore: enforce file extensions on imports
To make our output agnostic it should include file extensions in the
output, as per the ESM spec. It's a bit odd for Node packages but makes
it easier to publish a browser build.
This CL migrates all the tests to TypeScript. The main benefits of this is that we start consuming our TypeScript definitions and therefore find errors in them. The act of migrating found some bugs in our definitions and now we can be sure to avoid them going forwards.
You'll notice the addition of some `TODO`s in the code; I didn't want this CL to get any bigger than it already is but I intend to follow those up once this lands. It's mostly figuring out how to extend the `expect` types with our `toBeGolden` helpers and some other slight confusions with types that the tests exposed.
Co-authored-by: Mathias Bynens <mathias@qiwi.be>
