Misc SVG Viewer example fixes

Adds query parameters: `file` to specify different file and `scale` change the scale. Hash can be used to navigate to the page. Example: `http://localhost:8888/examples/svgviewer/index.html?scale=1.5&file=/web/compressed.tracemonkey-pldi-09.pdf#page=3`.

Also, fixed mistake in the rectange and restore.