Fix download button for top frames and sub frames
When PDF.js is the top frame, and the PDF URL is identical to
the top URL, download would fail. Fixed by adding a ? or & in these
cases.
When PDF.js is embedded in a frame from a different origin, download
would fail because window.open(url, '_parent') is ignored.
Fixed by using a.click() when available.
a.click() works in Chrome 25, Firefox 19, Opera 12.00 and IE 8.
Safari 5.1 does not support a.click()
Use a.download if available + documentation
88767e1861