--- a/devtools/client/debugger/content/views/sources-view.js
+++ b/devtools/client/debugger/content/views/sources-view.js
@@ -186,17 +186,16 @@ SourcesView.prototype = Heritage.extend(
   _addCommands: function () {
     XULUtils.addCommands(this._commandset, {
       addBreakpointCommand: e => this._onCmdAddBreakpoint(e),
       addConditionalBreakpointCommand: e => this._onCmdAddConditionalBreakpoint(e),
       blackBoxCommand: () => this.toggleBlackBoxing(),
       unBlackBoxButton: () => this._onStopBlackBoxing(),
       prettyPrintCommand: () => this.togglePrettyPrint(),
       toggleBreakpointsCommand: () =>this.toggleBreakpoints(),
-      togglePromiseDebuggerCommand: () => this.togglePromiseDebugger(),
       nextSourceCommand: () => this.selectNextItem(),
       prevSourceCommand: () => this.selectPrevItem()
     });
   },
 
   /**
    * Sets the preferred location to be selected in this sources container.
    * @param string aUrl
@@ -609,27 +608,16 @@ SourcesView.prototype = Heritage.extend(
       this._toggleBreakpointsButton.setAttribute("checked", true);
       this._onDisableAll();
     } else {
       this._toggleBreakpointsButton.removeAttribute("checked");
       this._onEnableAll();
     }
   },
 
-  togglePromiseDebugger: function () {
-    if (Prefs.promiseDebuggerEnabled) {
-      let promisePane = this.DebuggerView._promisePane;
-      promisePane.hidden = !promisePane.hidden;
-
-      if (!this.DebuggerView._promiseDebuggerIframe) {
-        this.DebuggerView._initializePromiseDebugger();
-      }
-    }
-  },
-
   hidePrettyPrinting: function () {
     this._prettyPrintButton.style.display = "none";
 
     if (this._blackBoxButton.style.display === "none") {
       let sep = document.querySelector("#sources-toolbar .devtools-separator");
       sep.style.display = "none";
     }
   },

--- a/devtools/client/debugger/debugger-controller.js
+++ b/devtools/client/debugger/debugger-controller.js
@@ -1206,17 +1206,16 @@ var Prefs = new PrefsHelper("devtools", 
   pauseOnExceptions: ["Bool", "debugger.pause-on-exceptions"],
   ignoreCaughtExceptions: ["Bool", "debugger.ignore-caught-exceptions"],
   sourceMapsEnabled: ["Bool", "debugger.source-maps-enabled"],
   prettyPrintEnabled: ["Bool", "debugger.pretty-print-enabled"],
   autoPrettyPrint: ["Bool", "debugger.auto-pretty-print"],
   workersEnabled: ["Bool", "debugger.workers"],
   editorTabSize: ["Int", "editor.tabsize"],
   autoBlackBox: ["Bool", "debugger.auto-black-box"],
-  promiseDebuggerEnabled: ["Bool", "debugger.promise"]
 });
 
 /**
  * Convenient way of emitting events from the panel window.
  */
 EventEmitter.decorate(this);
 
 /**

--- a/devtools/client/debugger/debugger-view.js
+++ b/devtools/client/debugger/debugger-view.js
@@ -18,18 +18,16 @@ const FUNCTION_SEARCH_ACTION_MAX_DELAY =
 const SEARCH_GLOBAL_FLAG = "!";
 const SEARCH_FUNCTION_FLAG = "@";
 const SEARCH_TOKEN_FLAG = "#";
 const SEARCH_LINE_FLAG = ":";
 const SEARCH_VARIABLE_FLAG = "*";
 const SEARCH_AUTOFILL = [SEARCH_GLOBAL_FLAG, SEARCH_FUNCTION_FLAG, SEARCH_TOKEN_FLAG];
 const TOOLBAR_ORDER_POPUP_POSITION = "topcenter bottomleft";
 const RESIZE_REFRESH_RATE = 50; // ms
-const PROMISE_DEBUGGER_URL =
-  "chrome://devtools/content/promisedebugger/promise-debugger.xhtml";
 
 const EventListenersView = require("./content/views/event-listeners-view");
 const SourcesView = require("./content/views/sources-view");
 var actions = Object.assign(
   {},
   require("./content/globalActions"),
   require("./content/actions/breakpoints"),
   require("./content/actions/sources"),
@@ -130,17 +128,16 @@ var DebuggerView = {
     this.Filtering.destroy();
     this.StackFrames.destroy();
     this.StackFramesClassicList.destroy();
     this.Sources.destroy();
     this.VariableBubble.destroy();
     this.WatchExpressions.destroy();
     this.EventListeners.destroy();
     this.GlobalSearch.destroy();
-    this._destroyPromiseDebugger();
     this._destroyPanes();
 
     this.editor.destroy();
     this.editor = null;
 
     this.controller.dispatch(actions.removeAllBreakpoints());
   },
 
@@ -150,17 +147,16 @@ var DebuggerView = {
   _initializePanes: function () {
     dumpn("Initializing the DebuggerView panes");
 
     this._body = document.getElementById("body");
     this._editorDeck = document.getElementById("editor-deck");
     this._workersAndSourcesPane = document.getElementById("workers-and-sources-pane");
     this._instrumentsPane = document.getElementById("instruments-pane");
     this._instrumentsPaneToggleButton = document.getElementById("instruments-pane-toggle");
-    this._promisePane = document.getElementById("promise-debugger-pane");
 
     this.showEditor = this.showEditor.bind(this);
     this.showBlackBoxMessage = this.showBlackBoxMessage.bind(this);
     this.showProgressBar = this.showProgressBar.bind(this);
 
     this._onTabSelect = this._onInstrumentsPaneTabSelect.bind(this);
     this._instrumentsPane.tabpanels.addEventListener("select", this._onTabSelect);
 
@@ -186,17 +182,16 @@ var DebuggerView = {
     if (gHostType != "side") {
       Prefs.workersAndSourcesWidth = this._workersAndSourcesPane.getAttribute("width");
       Prefs.instrumentsWidth = this._instrumentsPane.getAttribute("width");
     }
 
     this._workersAndSourcesPane = null;
     this._instrumentsPane = null;
     this._instrumentsPaneToggleButton = null;
-    this._promisePane = null;
   },
 
   /**
    * Initializes the VariablesView instance and attaches a controller.
    */
   _initializeVariablesView: function () {
     this.Variables = new VariablesView(document.getElementById("variables"), {
       searchPlaceholder: L10N.getStr("emptyVariablesFilterText"),
@@ -234,51 +229,16 @@ var DebuggerView = {
         case "properties":
           window.emit(EVENTS.FETCHED_PROPERTIES);
           break;
       }
     });
   },
 
   /**
-   * Initialie the Promise Debugger instance.
-   */
-  _initializePromiseDebugger: function () {
-    let iframe = this._promiseDebuggerIframe = document.createElement("iframe");
-    iframe.setAttribute("flex", 1);
-
-    let onLoad = (event) => {
-      iframe.removeEventListener("load", onLoad, true);
-
-      let doc = event.target;
-      let win = doc.defaultView;
-
-      win.setPanel(DebuggerController._toolbox);
-    };
-
-    iframe.addEventListener("load", onLoad, true);
-    iframe.setAttribute("src", PROMISE_DEBUGGER_URL);
-    this._promisePane.appendChild(iframe);
-  },
-
-  /**
-   * Destroy the Promise Debugger instance.
-   */
-  _destroyPromiseDebugger: function () {
-    if (this._promiseDebuggerIframe) {
-      this._promiseDebuggerIframe.contentWindow.destroy();
-
-      this._promiseDebuggerIframe.parentNode.removeChild(
-        this._promiseDebuggerIframe);
-
-      this._promiseDebuggerIframe = null;
-    }
-  },
-
-  /**
    * Initializes the Editor instance.
    *
    * @param function aCallback
    *        Called after the editor finishes initializing.
    */
   _initializeEditor: function (callback) {
     dumpn("Initializing the DebuggerView editor");
 

--- a/devtools/client/debugger/debugger.xul
+++ b/devtools/client/debugger/debugger.xul
@@ -336,21 +336,16 @@
                                  command="prettyPrintCommand"
                                  hidden="true"/>
                 </hbox>
                 <vbox class="devtools-separator"/>
                 <toolbarbutton id="toggle-breakpoints"
                                class="devtools-toolbarbutton"
                                tooltiptext="&debuggerUI.sources.toggleBreakpoints;"
                                command="toggleBreakpointsCommand"/>
-                <toolbarbutton id="toggle-promise-debugger"
-                               class="devtools-toolbarbutton"
-                               tooltiptext="&debuggerUI.sources.togglePromiseDebugger;"
-                               command="togglePromiseDebuggerCommand"
-                               hidden="true"/>
               </toolbar>
             </tabpanel>
             <tabpanel id="callstack-tabpanel">
               <vbox id="callstack-list" flex="1"/>
             </tabpanel>
           </tabpanels>
         </tabbox>
       </vbox>
@@ -398,22 +393,16 @@
                 <vbox id="variables" flex="1"/>
               </tabpanel>
               <tabpanel id="events-tabpanel">
                 <vbox id="event-listeners" flex="1"/>
               </tabpanel>
             </tabpanels>
           </tabbox>
         </hbox>
-        <splitter id="editor-and-promise-splitter"
-                class="devtools-horizontal-splitter"/>
-        <vbox id="promise-debugger-pane"
-              flex="1"
-              hidden="true">
-        </vbox>
       </vbox>
       <splitter id="vertical-layout-splitter"
                 class="devtools-horizontal-splitter"/>
       <hbox id="vertical-layout-panes-container">
         <splitter id="sources-and-instruments-splitter"
                   class="devtools-side-splitter"/>
         <!-- The sources-pane and instruments-pane will be moved in this
              container if the toolbox's host requires it. -->

--- a/devtools/client/debugger/test/mochitest/browser_dbg_host-layout.js
+++ b/devtools/client/debugger/test/mochitest/browser_dbg_host-layout.js
@@ -120,49 +120,43 @@ function testHost(aPanel, aHostType, aLa
   is(gView._body.getAttribute("layout"), aLayoutType,
     "The default host type is present as an attribute on the panel's body.");
 
   if (aLayoutType == "horizontal") {
     is(gView._workersAndSourcesPane.parentNode.id, "debugger-widgets",
       "The workers and sources pane's parent is correct for the horizontal layout.");
     is(gView._instrumentsPane.parentNode.id, "editor-and-instruments-pane",
       "The instruments pane's parent is correct for the horizontal layout.");
-    is(gDebugger.document.getElementById("promise-debugger-pane").parentNode.id,
-      "debugger-content",
-      "The promise pane's parent is correct for the horizontal layout.");
   } else {
     is(gView._workersAndSourcesPane.parentNode.id, "vertical-layout-panes-container",
       "The workers and sources pane's parent is correct for the vertical layout.");
     is(gView._instrumentsPane.parentNode.id, "vertical-layout-panes-container",
       "The instruments pane's parent is correct for the vertical layout.");
-    is(gDebugger.document.getElementById("promise-debugger-pane").parentNode.id,
-      "debugger-content",
-      "The promise pane's parent is correct for the horizontal layout.");
   }
 
   let widgets = gDebugger.document.getElementById("debugger-widgets").childNodes;
   let content = gDebugger.document.getElementById("debugger-content").childNodes;
   let editorPane =
     gDebugger.document.getElementById("editor-and-instruments-pane").childNodes;
   let verticalPane =
     gDebugger.document.getElementById("vertical-layout-panes-container").childNodes;
 
   if (aLayoutType == "horizontal") {
     is(widgets.length, 5, // 1 pane, 1 content box, 2 splitters and a phantom box.
       "Found the correct number of debugger widgets.");
-    is(content.length, 3, // 2 panes, 1 splitter.
+    is(content.length, 1, // 1 pane
       "Found the correct number of debugger content.");
     is(editorPane.length, 3, // 2 panes, 1 splitter
       "Found the correct number of debugger panes.");
     is(verticalPane.length, 1, // 1 lonely splitter in the phantom box.
       "Found the correct number of debugger panes.");
   } else {
     is(widgets.length, 4, // 1 content box, 2 splitters and a phantom box.
       "Found the correct number of debugger widgets.");
-    is(content.length, 3, // 2 panes, 1 splitter.
+    is(content.length, 1, // 1 pane
       "Found the correct number of debugger content.");
     is(editorPane.length, 2, // 1 pane, 1 splitter
       "Found the correct number of debugger panes.");
     is(verticalPane.length, 3, // 2 panes and 1 splitter in the phantom box.
       "Found the correct number of debugger panes.");
   }
 }
 

--- a/devtools/client/jar.mn
+++ b/devtools/client/jar.mn
@@ -96,19 +96,16 @@ devtools.jar:
     content/performance/views/details-waterfall.js (performance/views/details-waterfall.js)
     content/performance/views/details-js-call-tree.js (performance/views/details-js-call-tree.js)
     content/performance/views/details-js-flamegraph.js (performance/views/details-js-flamegraph.js)
     content/performance/views/details-memory-call-tree.js (performance/views/details-memory-call-tree.js)
     content/performance/views/details-memory-flamegraph.js (performance/views/details-memory-flamegraph.js)
     content/performance/views/recordings.js (performance/views/recordings.js)
     content/memory/memory.xhtml (memory/memory.xhtml)
     content/memory/initializer.js (memory/initializer.js)
-    content/promisedebugger/promise-controller.js (promisedebugger/promise-controller.js)
-    content/promisedebugger/promise-panel.js (promisedebugger/promise-panel.js)
-    content/promisedebugger/promise-debugger.xhtml (promisedebugger/promise-debugger.xhtml)
     content/commandline/commandline.css (commandline/commandline.css)
     content/commandline/commandlineoutput.xhtml (commandline/commandlineoutput.xhtml)
     content/commandline/commandlinetooltip.xhtml (commandline/commandlinetooltip.xhtml)
     content/framework/toolbox-window.xul (framework/toolbox-window.xul)
     content/framework/toolbox-options.xhtml (framework/toolbox-options.xhtml)
     content/framework/toolbox.xul (framework/toolbox.xul)
     content/framework/toolbox-init.js (framework/toolbox-init.js)
     content/framework/options-panel.css (framework/options-panel.css)

--- a/devtools/client/locales/en-US/debugger.dtd
+++ b/devtools/client/locales/en-US/debugger.dtd
@@ -45,20 +45,16 @@
   -  checkbox that toggles auto pretty print. -->
 <!ENTITY debuggerUI.autoPrettyPrint     "Auto Prettify Minified Sources">
 <!ENTITY debuggerUI.autoPrettyPrint.accesskey "P">
 
 <!-- LOCALIZATION NOTE (debuggerUI.sources.toggleBreakpoints): This is the tooltip for the
   -  button that toggles all breakpoints for all sources. -->
 <!ENTITY debuggerUI.sources.toggleBreakpoints "Enable/disable all breakpoints">
 
-<!-- LOCALIZATION NOTE (debuggerUI.sources.togglePromiseDebugger): This is the
-  -  tooltip for the button that toggles the promise debugger. -->
-<!ENTITY debuggerUI.sources.togglePromiseDebugger "Toggle Promise Debugger">
-
 <!-- LOCALIZATION NOTE (debuggerUI.clearButton): This is the label for
   -  the button that clears the collected tracing data in the tracing tab. -->
 <!ENTITY debuggerUI.clearButton "Clear">
 
 <!-- LOCALIZATION NOTE (debuggerUI.clearButton.tooltip): This is the tooltip for
   -  the button that clears the collected tracing data in the tracing tab. -->
 <!ENTITY debuggerUI.clearButton.tooltip "Clear the collected traces">
 

deleted file mode 100644
--- a/devtools/client/locales/en-US/promisedebugger.dtd
+++ /dev/null
@@ -1,15 +0,0 @@
-<!-- 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/. -->
-
-<!-- LOCALIZATION NOTE : FILE This file contains the Promise debugger panel
-     strings. The Promise debugger panel is part of the debugger -->
-<!-- LOCALIZATION NOTE : FILE Do not translate commandkey -->
-
-<!-- LOCALIZATION NOTE : FILE The correct localization of this file might be to
-  - keep it in English, or another language commonly spoken among web developers.
-  - You want to make that choice consistent across the developer tools.
-  - A good criteria is the language in which you'd find the best
-  - documentation on web development on the web. -->
-
-<!ENTITY title "Promise Debugger">

--- a/devtools/client/moz.build
+++ b/devtools/client/moz.build
@@ -17,17 +17,16 @@ DIRS += [
     'inspector',
     'jsonview',
     'locales',
     'memory',
     'netmonitor',
     'performance',
     'preferences',
     'projecteditor',
-    'promisedebugger',
     'responsive.html',
     'responsivedesign',
     'scratchpad',
     'shadereditor',
     'shared',
     'shims',
     'sourceeditor',
     'storage',

--- a/devtools/client/preferences/devtools.js
+++ b/devtools/client/preferences/devtools.js
@@ -95,17 +95,16 @@ pref("devtools.debugger.remote-timeout",
 pref("devtools.debugger.pause-on-exceptions", false);
 pref("devtools.debugger.ignore-caught-exceptions", true);
 pref("devtools.debugger.source-maps-enabled", true);
 pref("devtools.debugger.client-source-maps-enabled", true);
 pref("devtools.debugger.pretty-print-enabled", true);
 pref("devtools.debugger.auto-pretty-print", false);
 pref("devtools.debugger.auto-black-box", true);
 pref("devtools.debugger.workers", false);
-pref("devtools.debugger.promise", false);
 
 #if defined(NIGHTLY_BUILD)
 pref("devtools.debugger.new-debugger-frontend", true);
 #else
 pref("devtools.debugger.new-debugger-frontend", false);
 #endif
 
 // The default Debugger UI settings

deleted file mode 100644
--- a/devtools/client/promisedebugger/moz.build
+++ /dev/null
@@ -1,8 +0,0 @@
-# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
-# vim: set filetype=python:
-# 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/.
-
-DevToolsModules(
-)

deleted file mode 100644
--- a/devtools/client/promisedebugger/promise-controller.js
+++ /dev/null
@@ -1,102 +0,0 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
-/* 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/. */
-
-/* global PromisesPanel */
-
-"use strict";
-
-var { utils: Cu } = Components;
-const { loader, require } =
-  Cu.import("resource://devtools/shared/Loader.jsm", {});
-
-const { Task } = require("devtools/shared/task");
-
-loader.lazyRequireGetter(this, "promise");
-loader.lazyRequireGetter(this, "EventEmitter",
-  "devtools/shared/event-emitter");
-loader.lazyRequireGetter(this, "DevToolsUtils",
-  "devtools/shared/DevToolsUtils");
-loader.lazyRequireGetter(this, "PromisesFront",
-  "devtools/server/actors/promises", true);
-
-// Global toolbox, set when startup is called.
-var gToolbox;
-
-/**
- * Initialize the promise debugger controller and view upon loading the iframe.
- */
-var startup = Task.async(function* (toolbox) {
-  gToolbox = toolbox;
-
-  yield PromisesController.initialize(toolbox);
-  yield PromisesPanel.initialize();
-});
-
-/**
- * Destroy the promise debugger controller and view when unloading the iframe.
- */
-var shutdown = Task.async(function* () {
-  yield PromisesController.destroy();
-  yield PromisesPanel.destroy();
-
-  gToolbox = null;
-});
-
-function setPanel(toolbox) {
-  return startup(toolbox).catch(e =>
-    DevToolsUtils.reportException("setPanel", e));
-}
-
-function destroy() {
-  return shutdown().catch(e => DevToolsUtils.reportException("destroy", e));
-}
-
-/**
- * The promisedebugger controller's job is to retrieve PromisesFronts from the
- * server.
- */
-var PromisesController = {
-  initialize: Task.async(function* () {
-    if (this.initialized) {
-      return this.initialized.promise;
-    }
-
-    this.initialized = promise.defer();
-
-    let target = gToolbox.target;
-    this.promisesFront = new PromisesFront(target.client, target.form);
-    yield this.promisesFront.attach();
-
-    if (this.destroyed) {
-      console.warn("Could not fully initialize the PromisesController");
-      return null;
-    }
-
-    this.initialized.resolve();
-  }),
-
-  destroy: Task.async(function* () {
-    if (!this.initialized) {
-      return null;
-    }
-
-    if (this.destroyed) {
-      return this.destroyed.promise;
-    }
-
-    this.destroyed = promise.defer();
-
-    if (this.promisesFront) {
-      yield this.promisesFront.detach();
-      this.promisesFront.destroy();
-      this.promisesFront = null;
-    }
-
-    this.destroyed.resolve();
-  }),
-};
-
-EventEmitter.decorate(PromisesController);

deleted file mode 100644
--- a/devtools/client/promisedebugger/promise-debugger.xhtml
+++ /dev/null
@@ -1,21 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!-- This Source Code Form is subject to the terms of the Mkozilla 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/. -->
-
-<!DOCTYPE html [
-  <!ENTITY % promisedebuggerDTD SYSTEM "chrome://devtools/locale/promisedebugger.dtd">
-  %promisedebuggerDTD;
-]>
-
-<html xmlns="http://www.w3.org/1999/xhtml">
-  <head>
-    <title>&title;</title>
-    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
-    <script type="application/javascript;version=1.8" src="chrome://devtools/content/shared/theme-switching.js"/>
-  </head>
-  <body class="devtools-monospace" role="application">
-    <script type="application/javascript;version=1.8" src="promise-controller.js"></script>
-    <script type="application/javascript;version=1.8" src="promise-panel.js"></script>
-  </body>
-</html>

deleted file mode 100644
--- a/devtools/client/promisedebugger/promise-panel.js
+++ /dev/null
@@ -1,45 +0,0 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
-/* 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/. */
-
-/* global PromisesController, promise */
-/* import-globals-from promise-controller.js */
-
-"use strict";
-
-/**
- * The main promise debugger UI.
- */
-var PromisesPanel = {
-  PANEL_INITIALIZED: "panel-initialized",
-
-  initialize: Task.async(function* () {
-    if (PromisesController.destroyed) {
-      return null;
-    }
-    if (this.initialized) {
-      return this.initialized.promise;
-    }
-    this.initialized = promise.defer();
-
-    this.initialized.resolve();
-
-    this.emit(this.PANEL_INITIALIZED);
-  }),
-
-  destroy: Task.async(function* () {
-    if (!this.initialized) {
-      return null;
-    }
-    if (this.destroyed) {
-      return this.destroyed.promise;
-    }
-    this.destroyed = promise.defer();
-
-    this.destroyed.resolve();
-  }),
-};
-
-EventEmitter.decorate(PromisesPanel);

deleted file mode 100644
--- a/devtools/client/promisedebugger/test/.eslintrc.js
+++ /dev/null
@@ -1,6 +0,0 @@
-"use strict";
-
-module.exports = {
-  // Extend from the shared list of defined globals for mochitests.
-  "extends": "../../../.eslintrc.mochitests.js"
-};

deleted file mode 100644
--- a/devtools/client/promisedebugger/test/head.js
+++ /dev/null
@@ -1,4 +0,0 @@
-/* Any copyright is dedicated to the Public Domain.
-   http://creativecommons.org/publicdomain/zero/1.0/ */
-
-"use strict";

--- a/devtools/client/themes/debugger.css
+++ b/devtools/client/themes/debugger.css
@@ -124,20 +124,16 @@
   -moz-image-region: rect(0,16px,16px,0);
 }
 
 #toggle-breakpoints[checked] > image {
   /* This button has a special checked image, don't make it blue */
   filter: none;
 }
 
-#toggle-promise-debugger {
-  /* TODO Bug 1186119: Add a toggle promise debugger image */
-}
-
 #sources .black-boxed {
   color: rgba(128,128,128,0.4);
 }
 
 #sources .selected .black-boxed {
   color: rgba(255,255,255,0.4);
 }