How do they get other web pages, given cross-domain constraints? Are they downloading the page on the server into a headless browser like Phantom JS, and then delivering the result to your browser to be manipulated using WebGL and Javascript?<p>I get that there are capabilities like drawWindow() to turn parts of the dom into raster images programmatically, but how doe they suck the web page into your browser in the first place, given cross domain constraints???