Guard against unsupported non-standard contentEditable=plaintext-only
Guard against unsupported non-standard contentEditable=plaintext-only

poacher2k/vimium,philc/vimium,gdh1995/vimium,decaffeinate-examples/vimium,poacher2k/vimium,smblott-github/vimium,philc/vimium,gdh1995/vimium,smblott-github/vimium,decaffeinate-examples/vimium,mrmr1993/vimium,decaffeinate-examples/vimium,mrmr1993/vimium,smblott-github/vimium,mrmr1993/vimium,philc/vimium,gdh1995/vimium,poacher2k/vimium