Puppeteer captures wrong location of selectors / Chromy doesn't

[matthew-dean]

I was attempting to solve #785, which seems to be a problem in Chromy but not Puppeteer. But I had many, many displaced screenshots using Puppeteer that were not a problem with Chromy. Nothing else changed other than the engine.

Example (Running once with Chromy on left, Puppeteer is middle image):

Not sure why, but the selector "clipping" for the Puppeteer plugin seems to be entirely inaccurate.

[cactusa]

Have a look at #704