code: function openDocument(doc, pane, editorOptions) {
          var perfTimerName = PerfUtils.markStart("EditorManager.openDocument():\t" + (!doc || doc.file.fullPath));
  
          if (doc && pane) {
              _showEditor(doc, pane, editorOptions);
          }
  
          PerfUtils.addMeasurement(perfTimerName);
      }
docs: Opens the specified document in the given pane
  @param {!Document} doc - the document to open
  @param {!Pane} pane - the pane to open the document in
  @param {!Object} editorOptions - If specified, contains
  editor options that can be passed to CodeMirror
  @return {boolean} true if the file can be opened, false if not