Add browser.fork function that returns a promise

[juliemr]

This promise will resolve to the new browser instance, so it can be used nicely with await and in a control-flow-less world:

TODO - think of a better name.

let b2 = await browser.forkAndInitializeNewBrowserInstance();
await b2.get('example.com');
// continue to use b2 as a browser instance.

[sjelin]

Actually, it should probably just be an optional parameter to forkNewDriverInstance. Typescript can handle "return type X if param 3 is true, return type Y if param 3 is false". It sucks that it has to go at the end of the parameter list, but that's life I guess.

[juliemr]

What's your reasoning for that? Sure, we'll have a duplicate list of other parameters, but they can go to the same function under the hood.

[sjelin]

Just seems more natural? Maybe I'd feel better about separate functions if we could come up with a good name 😛

[sjelin]

Like, you rarely have two different functions that do almost exactly the same thing. It's pretty common to use params in this case, yeah?

[sjelin]

(Not a strongly held opinion though)

[sjelin]

As of version 5.1, you can do this indirectly by using .ready:

forkedBrowserPromise = browser.forkNewDriverInstance().ready

We may still implement this as its own function in the future, but it's not super high priority