Only use fallback viewer in WebKit/Blink, since that's the only place it works correctly.
Only use fallback viewer in WebKit/Blink, since that's the only place it works correctly.

quentinyang/pannellum,Benvii/pannellum,psteph801/psteph801.github.io,ywjrg/pannellum,ywjrg/pannellum,ywjrg/pannellum,mpetroff/pannellum,Benvii/pannellum,eric-seekas/pannellum,quentinyang/pannellum,riuson/pannellum,psteph801/psteph801.github.io,riuson/pannellum,psteph801/psteph801.github.io,quentinyang/pannellum,ywjrg/pannellum,mpetroff/pannellum,riuson/pannellum,Benvii/pannellum,mpetroff/pannellum,Benvii/pannellum,psteph801/psteph801.github.io,eric-seekas/pannellum,eric-seekas/pannellum,riuson/pannellum,quentinyang/pannellum,mpetroff/pannellum,eric-seekas/pannellum