Reported (actual) resolution differs between Quick Scan and Full Scan on Firefox

[octavn]

There's a strange bug I noticed on both Firefox 49 and 50 where the Actual reported resolution differs between Quick Scan and FullScan.

For example:

• requesting the 640x360 (360p(nHD)) resolution through Quick Scan results in 640x480 Actual resolution.

• requesting the 640x360 (360p(nHD)) resolution through Full Scan results in 0x0 Actual resolution.

I was able to reproduce with 400x300 as well. I could not reproduce the issue on Chrome.