fix: bug fixes from linters (#1524)

packages/netlify-cms-widget-markdown/src/MarkdownControl/Toolbar.js

@@ -55,7 +55,7 @@ const ToolbarToggleLabel = styled.span`
 
 export default class Toolbar extends React.Component {
   static propTypes = {
-    buttons: PropTypes.object,
+    buttons: ImmutablePropTypes.list,
     onToggleMode: PropTypes.func.isRequired,
     rawMode: PropTypes.bool,
     plugins: ImmutablePropTypes.map,
@@ -63,7 +63,6 @@ export default class Toolbar extends React.Component {
     onAddAsset: PropTypes.func,
     getAsset: PropTypes.func,
     disabled: PropTypes.bool,
-    buttons: ImmutablePropTypes.list
   };
 
   constructor(props) {

packages/netlify-cms-widget-markdown/src/serializers/remarkShortcodes.js

@@ -45,7 +45,7 @@ export default function remarkShortcodes({ plugins }) {
      * included. Otherwise, return the original node.
      */
     return matchIsValid ? createShortcodeNode(text, plugin, match) : node;
-  };
+  }
 
   /**
    * Ensure that the node and it's children are acceptable types to contain