Calculating the viewport for an SVG. View source for the function, or see "Determining the SVG viewport in global/root coordinates" for details.
If you do NOT see a green stroke exactly around the white box at any point, the
calculateViewport() function is not working correctly.
Copyright 2014 Gavin Kistner. Reuse permitted under the license terms at http://phrogz.net/JS/_ReuseLicense.txt