Fix error in processor.js when using the vision_deficiency option

[julianwegkamp]

Fixes the error in processor.js when using the vision_deficiency option as reported in issue #127.

Added a spec as you suggested, but I'm running into some strange behavior. On some test runs the mean_colour_statistics returns ["94", "71", "0"] (which I assume is correct) on other runs it returns ["240.506", "240.527", "242.569"]. This is likely the mean color from the page http://www.example.net/foo/bar. Do you recognize this inconsistency while running the specs?

1) Grover::Processor#convert when converting to an image when vision deficiency is set to `deuteranopia` is expected to eq ["94", "71", "0"]
  Failure/Error: it { expect(mean_colour_statistics(image)).to eq %w[94 71 0] }
  
    expected: ["94", "71", "0"]
        got: ["240.506", "240.527", "242.569"]
  
    (compared using ==)
  # ./spec/grover/processor_spec.rb:837:in `block (5 levels) in <top (required)>'

[abrom]

Thanks @julianwegkamp 👍

FYI I figured out the cause of the weird results you were seeing. It was caused by two different issues. First, it seems like the emulateVisionDeficiency method needs to be called after the content has been rendered. The documentation doesn't suggest this needs to be the case but I can say that it fails pretty reliably if it isn't afterward! Second, I had missed adding an await clause on that call meaning that it was applying the setting asynchronously. This would explain why it would sometimes work and other times not. On the occasions where it worked it was running after the content was rendered. The times when it didn't it appears to have actually broken the rendering mechanism completely. Those numbers coincide with what you see when the renderer doesn't capture the request and it actually goes out to the internet to fetch "example.com". i.e:

I noticed a few other places where I had not included the await clause so I've fixed them up too.

Thanks again

[abrom]

FYI released in v1.0.5

[julianwegkamp]

Thx