[merge addon] Fix typo in hasMarker()
[merge addon] Fix typo in hasMarker()

This was causing exceptions to be thrown when using custom
markers.

hackmdio/CodeMirror,dperetti/CodeMirror,codio/CodeMirror,nightwing/CodeMirror,codio/CodeMirror,hackmdio/CodeMirror,nightwing/CodeMirror,thomasjm/CodeMirror,codio/CodeMirror,notepadqq/CodeMirror,mtaran-google/CodeMirror,hackmdio/CodeMirror,pabloferz/CodeMirror,pabloferz/CodeMirror,mtaran-google/CodeMirror,nightwing/CodeMirror,notepadqq/CodeMirror,notepadqq/CodeMirror,thomasjm/CodeMirror,wingify/CodeMirror,pabloferz/CodeMirror,dperetti/CodeMirror,wingify/CodeMirror,mtaran-google/CodeMirror,thomasjm/CodeMirror,wingify/CodeMirror,dperetti/CodeMirror