fix small code issues in RTE implementation

src/components/PreviewPane/Preview.js

@@ -9,6 +9,10 @@ const style = {
   fontFamily: 'Roboto, "Helvetica Neue", HelveticaNeue, Helvetica, Arial, sans-serif',
 };
 
+/**
+ * Use a stateful component so that child components can effectively utilize
+ * `shouldComponentUpdate`.
+ */
 export default class Preview extends React.Component {
   render() {
     const { collection, fields, widgetFor } = this.props;

src/components/PreviewPane/PreviewContent.js

@@ -1,9 +1,11 @@
 import React, { PropTypes } from 'react';
 import { ScrollSyncPane } from '../ScrollSync';
 
-// We need to create a lightweight component here so that we can
-// access the context within the Frame. This allows us to attach
-// the ScrollSyncPane to the body.
+/**
+ * We need to create a lightweight component here so that we can access the
+ * context within the Frame. This allows us to attach the ScrollSyncPane to the
+ * body.
+ */
 class PreviewContent extends React.Component {
   render() {
     const { previewComponent, previewProps } = this.props;

src/components/PreviewPane/PreviewPane.js

@@ -17,6 +17,9 @@ export default class PreviewPane extends React.Component {
     const { fieldsMetaData, getAsset, entry } = props;
     const widget = resolveWidget(field.get('widget'));
 
+    /**
+     * Use an HOC to provide conditional updates for all previews.
+     */
     return !widget.preview ? null : (
       <PreviewHOC
         previewComponent={widget.preview}

src/components/Widgets/ControlHOC.js

@@ -1,6 +1,5 @@
 import React, { Component, PropTypes } from 'react';
 import ImmutablePropTypes from "react-immutable-proptypes";
-import isEqual from 'lodash/isEqual';
 
 const truthy = () => ({ error: false });
 

src/components/Widgets/Markdown/serializers/remarkSquashReferences.js

@@ -19,7 +19,7 @@ import mdastDefinitions from 'mdast-util-definitions';
  * Yields:
  *
  * ```
- * ![alpha][http://example.com/example.jpg]
+ * ![alpha](http://example.com/example.jpg)
  * ```
  *
  */

src/components/Widgets/PreviewHOC.js

@@ -1,10 +1,13 @@
 import React from 'react';
 
 class PreviewHOC extends React.Component {
+
+  /**
+   * Only re-render on value change, but always re-render objects and lists.
+   * Their child widgets will each also be wrapped with this component, and
+   * will only be updated on value change.
+   */
   shouldComponentUpdate(nextProps) {
-    // Only re-render on value change, but always re-render objects and lists.
-    // Their child widgets will each also be wrapped with this component, and
-    // will only be updated on value change.
     const isWidgetContainer = ['object', 'list'].includes(nextProps.field.get('widget'));
     return isWidgetContainer || this.props.value !== nextProps.value;
   }