Remove diff summary from document history sidebar.

Cause of occassional memory leaks and downtime :(

app/components/DocumentHistory/DocumentHistory.js

@@ -82,12 +82,6 @@ class DocumentHistory extends React.Component<Props> {
 
   render() {
     const showLoading = !this.isLoaded && this.isFetching;
-    const maxChanges = this.revisions.reduce((acc, change) => {
-      if (acc < change.diff.added + change.diff.removed) {
-        return change.diff.added + change.diff.removed;
-      }
-      return acc;
-    }, 0);
 
     return (
       <Wrapper column>
@@ -105,7 +99,6 @@ class DocumentHistory extends React.Component<Props> {
                 key={revision.id}
                 revision={revision}
                 document={this.props.document}
-                maxChanges={maxChanges}
                 showMenu={index !== 0}
               />
             ))}