Restarting forked browsers is broken

[sjelin]

Let's say you do the following:

let b2 = browser. forkNewDriverInstance()
b2.restart()

Because restart assumes it's being called against the global browser instance, the global browser instance will be overwritten with the restarted b2 instance, and b2 will still be pointing to original (now closed) forked instance.

I propose we have restart return the new instance. We can still overwrite the global instance when appropriate too (just add an if statement here). So now the code will be:

let b2 = browser. forkNewDriverInstance()
b2 = b2.restart()

Whatever we end up doing to forkNewDriverInstance in #3892 we'll have to also do to restart for async/await users.

[sjelin]

Fixed by b77cb92