Retain the TextBuffer within a PatchBuffer

Author: smashwilson

lib/models/patch/patch-buffer.js

@@ -6,6 +6,8 @@ const LAYER_NAMES = ['unchanged', 'addition', 'deletion', 'nonewline', 'hunk', '
 export default class PatchBuffer {
   constructor() {
     this.buffer = new TextBuffer();
+    this.buffer.retain();
+
     this.layers = LAYER_NAMES.reduce((map, layerName) => {
       map[layerName] = this.buffer.addMarkerLayer();
       return map;