Options windowSize and captureSelector do not work together

[maksim-zhuk]

When captureSelector option is set, windowSize is being ignored. It would be nice to have an option to specify a block selector and limit an output image with windowSize/shotSize parameters.

[nicholasblexrud]

@maksim-zhuk this might be an issue with phantomjs. Take a look at this issue in phantom js and let me know if it is the same issue as you're describing: Render not honoring viewport size.

[maksim-zhuk]

@nicholasblexrud Don't think these are related.
Both _ captureSelector_ and _ windowSize_ options work perfectly well, my point is that they do not work properly together.

Imagine like when you open any image in a browser, limit the browser's visible area to the half of an image and make a snapshot. The captured result would be only the visible part of an image.
Same is here: when range of captureSelector is calculated it should be cropped to windowSize before being passed to renderer.

P.S. I might be conceptually wrong and when captureSelector option is set then no other size-related options (windowSize, shotSize , shotOffset) should take effect, but in this case it might make sense to describe this behavior in docs.