STR: 1. Go to http://www.penny-arcade.com/patv/pa-the-series/214/ 2. Bring up the add-on bar with command-/. 3. Click on the x to the left of the bar to close it. 4. Rinse, repeat, until it crashes. https://crash-stats.mozilla.com/report/index/106d7933-bc1e-4c99-9a6e-cd2012110301
I get this without a persona, too. Should be easy to reproduce.
We're hitting one of the |return false;| cases in http://mxr.mozilla.org/mozilla-central/source/dom/plugins/NPEventOSX.h#115 . There's not enough information in the report to tell which.
Resolving old bugs which are likely not relevant any more, since NPAPI plugins are deprecated.