code: function setFontSize(fontSize) {
          if (currFontSize === fontSize) {
              return;
          }
  
          _removeDynamicFontSize();
          if (fontSize) {
              _addDynamicFontSize(fontSize);
          }
  
          // Update scroll metrics in viewed editors
          _.forEach(MainViewManager.getPaneIdList(), function (paneId) {
              var currentPath = MainViewManager.getCurrentlyViewedPath(paneId),
                  doc = currentPath && DocumentManager.getOpenDocumentForPath(currentPath);
              if (doc && doc._masterEditor) {
                  _updateScroll(doc._masterEditor, fontSize);
              }
          });
  
          exports.trigger("fontSizeChange", fontSize, currFontSize);
          currFontSize = fontSize;
          prefs.set("fontSize", fontSize);
      }
docs: Font size setter to set the font size for the document editor
  @param {string} fontSize The font size with size unit as 'px' or 'em'