CodeMirror: using extendDoc.

Thanks to Wout Mertens for pointing this out.

Signed-off-by: Thaddee Tyl <thaddee.tyl@gmail.com>

src/client/cm.coffee

@@ -31,15 +31,15 @@ applyToShareJS = (editorDoc, delta, doc) ->
 # Attach a CodeMirror editor to the document. The editor's contents are replaced
 # with the document's contents unless keepEditorContents is true. (In which case
 # the document's contents are nuked and replaced with the editor's).
-window.sharejs.Doc::attach_cm = (editor, keepEditorContents) ->
+window.sharejs.extendDoc 'attach_cm', (editor, keepEditorContents) ->
   unless @provides.text
     throw new Error 'Only text documents can be attached to CodeMirror2'
 
   sharedoc = @
   check = ->
     window.setTimeout ->
         editorText = editor.getValue()
-        otText = sharedoc.getText()
+        otText = sharedoc.snapshot
 
         if editorText != otText
           console.error "Text does not match!"