- This patch uncomments a large portion of the Firefox specific code in viewer.js, by using a preprocessor "trick", to enable linting. Doing this actually uncovered some issues, e.g. variables defined multiple times.
- This patch also fixes a spelling error, `adobe pdfwritter` -> `abobe pdfwriter`, in the `KNOWN_GENERATORS` list used when reporting telemetry data in Firefox.
*Please note:* there's still some Firefox specific code that is commented out, but it's usually just one (or two) lines of code. Hence the risk that errors creep in should be much lower, compared to entire code-blocks.