Bug 1774631 - Fix typo in cairo-pdf-surface.c that causes us to get...

Bug 1774631 - Fix typo in cairo-pdf-surface.c that causes us to get spuriously-rasterized PDF output. r=jrmuizel, a=RyanVM

There's a typo in the condition here, which results in returning CAIRO_INT_STATUS_UNSUPPORTED
in cases where that shouldn't be necessary. Fixing this gets me nice vector PDF output.

The bug is still present in upstream cairo trunk, so I'll report it there as well.

Differential Revision: https://phabricator.services.mozilla.com/D150381