CSSPreprocessorDocument = function CSSPreprocessorDocument(doc, editor) {
        this.doc = doc;

        this.onCursorActivity = this.onCursorActivity.bind(this);

        // Add a ref to the doc since we're listening for change events
        this.doc.addRef();
        this.onActiveEditorChange = this.onActiveEditorChange.bind(this);
        EditorManager.on("activeEditorChange", this.onActiveEditorChange);
        this.onActiveEditorChange(null, EditorManager.getActiveEditor(), null);
    }
@constructor
@param {!Document} doc The source document from Brackets
@param {?Editor} editor The editor for this document. This is not used here since
                 we always need to get the active editor for a preprocessor document
                 and not the one passed in `editor`.