--- a/devtools/client/inspector/rules/rules.js
+++ b/devtools/client/inspector/rules/rules.js
@@ -26,20 +26,20 @@ const {
   VIEW_NODE_SHAPE_SWATCH,
   VIEW_NODE_VARIABLE_TYPE,
   VIEW_NODE_FONT_TYPE,
 } = require("devtools/client/inspector/shared/node-types");
 const TooltipsOverlay = require("devtools/client/inspector/shared/tooltips-overlay");
 const {createChild, promiseWarn} = require("devtools/client/inspector/shared/utils");
 const {debounce} = require("devtools/shared/debounce");
 const EventEmitter = require("devtools/shared/event-emitter");
-const AutocompletePopup = require("devtools/client/shared/autocomplete-popup");
 
 loader.lazyRequireGetter(this, "ClassListPreviewer", "devtools/client/inspector/rules/views/class-list-previewer");
 loader.lazyRequireGetter(this, "StyleInspectorMenu", "devtools/client/inspector/shared/style-inspector-menu");
+loader.lazyRequireGetter(this, "AutocompletePopup", "devtools/client/shared/autocomplete-popup");
 loader.lazyRequireGetter(this, "KeyShortcuts", "devtools/client/shared/key-shortcuts");
 loader.lazyRequireGetter(this, "clipboardHelper", "devtools/shared/platform/clipboard");
 
 const HTML_NS = "http://www.w3.org/1999/xhtml";
 const PREF_UA_STYLES = "devtools.inspector.showUserAgentStyles";
 const PREF_DEFAULT_COLOR_UNIT = "devtools.defaultColorUnit";
 const PREF_FONT_EDITOR = "devtools.inspector.fonteditor.enabled";
 const FILTER_CHANGED_TIMEOUT = 150;
@@ -171,22 +171,16 @@ function CssRuleView(inspector, document
 
   this._prefObserver = new PrefObserver("devtools.");
   this._prefObserver.on(PREF_UA_STYLES, this._handleUAStylePrefChange);
   this._prefObserver.on(PREF_DEFAULT_COLOR_UNIT, this._handleDefaultColorUnitPrefChange);
 
   this.showUserAgentStyles = Services.prefs.getBoolPref(PREF_UA_STYLES);
   this.showFontEditor = Services.prefs.getBoolPref(PREF_FONT_EDITOR);
 
-  // The popup will be attached to the toolbox document.
-  this.popup = new AutocompletePopup(inspector._toolbox.doc, {
-    autoSelect: true,
-    theme: "auto"
-  });
-
   this._showEmpty();
 
   // Add the tooltips and highlighters to the view
   this.tooltips = new TooltipsOverlay(this);
 
   this.highlighters.addToView(this);
 }
 
@@ -196,16 +190,28 @@ CssRuleView.prototype = {
 
   // Used for cancelling timeouts in the style filter.
   _filterChangedTimeout: null,
 
   // Empty, unconnected element of the same type as this node, used
   // to figure out how shorthand properties will be parsed.
   _dummyElement: null,
 
+  get popup() {
+    if (!this._popup) {
+      // The popup will be attached to the toolbox document.
+      this._popup = new AutocompletePopup(this.inspector.toolbox.doc, {
+        autoSelect: true,
+        theme: "auto",
+      });
+    }
+
+    return this._popup;
+  },
+
   get classListPreviewer() {
     if (!this._classListPreviewer) {
       this._classListPreviewer = new ClassListPreviewer(this.inspector, this.classPanel);
     }
 
     return this._classListPreviewer;
   },
 
@@ -779,17 +785,20 @@ CssRuleView.prototype = {
     if (this.element.parentNode) {
       this.element.remove();
     }
 
     if (this._elementStyle) {
       this._elementStyle.destroy();
     }
 
-    this.popup.destroy();
+    if (this._popup) {
+      this._popup.destroy();
+      this._popup = null;
+    }
   },
 
   /**
    * Mark the view as selecting an element, disabling all interaction, and
    * visually clearing the view after a few milliseconds to avoid confusion
    * about which element's styles the rule view shows.
    */
   _startSelectingElement: function() {

--- a/devtools/client/shared/autocomplete-popup.js
+++ b/devtools/client/shared/autocomplete-popup.js
@@ -1,23 +1,24 @@
 /* vim: set ft=javascript ts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
-const HTML_NS = "http://www.w3.org/1999/xhtml";
 const Services = require("Services");
+const EventEmitter = require("devtools/shared/event-emitter");
 const {HTMLTooltip} = require("devtools/client/shared/widgets/tooltip/HTMLTooltip");
-const EventEmitter = require("devtools/shared/event-emitter");
 const {PrefObserver} = require("devtools/client/shared/prefs");
 const {colorUtils} = require("devtools/shared/css/color");
 
+const HTML_NS = "http://www.w3.org/1999/xhtml";
 let itemIdCounter = 0;
+
 /**
  * Autocomplete popup UI implementation.
  *
  * @constructor
  * @param {Document} toolboxDoc
  *        The toolbox document to attach the autocomplete popup panel.
  * @param {Object} options
  *        An object consiting any of the following options: