When I tried saving a file on partition with no free space, Mozilla reported Out of Memory and advised me to shut down some apps to free up memory. This, of course, didn't and wouldn't help since I had plenty free memory. The only problem was the free space on target partition. Reproducible: Always Steps to Reproduce: 1. Save file as..., link target as... to partition with no free space. Actual Results: Out of Memory error message box. Expected Results: Out of Disk Space error message box...
Not something Gentoo should fix, please report this problem upstream (https://bugzilla.mozilla.org/) and post the URL here. Thanks.
Posted upstream https://bugzilla.mozilla.org/show_bug.cgi?id=317994