Fix 2636 (#3206)

* Fix 2636 Can't scroll to bottom of editor pane

* Fix minor lint issues

browser/components/MarkdownPreview.js

@@ -41,7 +41,6 @@ const CSS_FILES = [
   `${appPath}/node_modules/codemirror/lib/codemirror.css`,
   `${appPath}/node_modules/react-image-carousel/lib/css/main.min.css`
 ]
-const win = global.process.platform === 'win32'
 
 function buildStyle (
   fontFamily,
@@ -815,6 +814,7 @@ export default class MarkdownPreview extends React.Component {
             canvas.height = height.value + 'vh'
           }
 
+          // eslint-disable-next-line no-unused-vars
           const chart = new Chart(canvas, chartConfig)
         } catch (e) {
           el.className = 'chart-error'