Add caps to desktop_web_driver setup

[alexh-sauce]

caps was being configured but not passed to the webdriver for desktop tests.

[joshmgrant]

Approved! @alexh-sauce This was an oversight and you are correct to use caps in this PR.

[alexh-sauce]

@joshmgrant thanks, can you merge? I don't have permission.

[joshmgrant]

I do not have merge permissions (sadly). I'd ask @titusfortner or Stuart Minchington

[titusfortner]

Desired capabilities is deprecated. It should be options. what are you trying to do?

[alexh-sauce]

Right now the desktop_web_driver() function is broken because the caps dict is set, but never referenced. I'd like the test to use the caps the same way as mobile_web_driver(). However we get there is fine with me.

[joshmgrant]

I thought this was the case. I approved this PR since I thought (and could be very wrong about!) the Python bindings automatically handle desired_capabilities and turn them into an options object but I may be incorrect about this. Whatever y'all need to do here is fine.