Consider devicePixelRatio when calculating viewport
Consider devicePixelRatio when calculating viewport

This should fix #2635, fix #2633 and fix #2620.

gdh1995/vimium,philc/vimium,decaffeinate-examples/vimium,gdh1995/vimium,smblott-github/vimium,poacher2k/vimium,mrmr1993/vimium,mrmr1993/vimium,smblott-github/vimium,mrmr1993/vimium,philc/vimium,gdh1995/vimium,philc/vimium,poacher2k/vimium,decaffeinate-examples/vimium,poacher2k/vimium,decaffeinate-examples/vimium,smblott-github/vimium