--- a/browser/base/content/browser-devedition.js
+++ b/browser/base/content/browser-devedition.js
@@ -20,17 +20,16 @@ var DevEdition = {
     let theme = LightweightThemeManager.currentTheme;
     return theme && theme.id == "firefox-devedition@mozilla.org";
   },
 
   init() {
     this.initialized = true;
     Services.prefs.addObserver(this._devtoolsThemePrefName, this, false);
     Services.obs.addObserver(this, "lightweight-theme-styling-update", false);
-    Services.obs.addObserver(this, "lightweight-theme-window-updated", false);
     this._updateDevtoolsThemeAttribute();
 
     if (this.isThemeCurrentlyApplied) {
       this._toggleStyleSheet(true);
     }
   },
 
   createStyleSheet() {
@@ -45,18 +44,16 @@ var DevEdition = {
   observe(subject, topic, data) {
     if (topic == "lightweight-theme-styling-update") {
       let newTheme = JSON.parse(data);
       if (newTheme && newTheme.id == "firefox-devedition@mozilla.org") {
         this._toggleStyleSheet(true);
       } else {
         this._toggleStyleSheet(false);
       }
-    } else if (topic == "lightweight-theme-window-updated" && subject == window) {
-      this._updateLWTBrightness();
     }
 
     if (topic == "nsPref:changed" && data == this._devtoolsThemePrefName) {
       this._updateDevtoolsThemeAttribute();
     }
   },
 
   _inferBrightness() {
@@ -65,33 +62,24 @@ var DevEdition = {
     if (this.isStyleSheetEnabled &&
         document.documentElement.getAttribute("devtoolstheme") == "dark") {
       document.documentElement.setAttribute("brighttitlebarforeground", "true");
     } else {
       document.documentElement.removeAttribute("brighttitlebarforeground");
     }
   },
 
-  _updateLWTBrightness() {
-    if (this.isThemeCurrentlyApplied) {
-      let devtoolsTheme = Services.prefs.getCharPref(this._devtoolsThemePrefName);
-      let textColor = devtoolsTheme == "dark" ? "bright" : "dark";
-      document.documentElement.setAttribute("lwthemetextcolor", textColor);
-    }
-  },
-
   _updateDevtoolsThemeAttribute() {
     // Set an attribute on root element to make it possible
     // to change colors based on the selected devtools theme.
     let devtoolsTheme = Services.prefs.getCharPref(this._devtoolsThemePrefName);
     if (devtoolsTheme != "dark") {
       devtoolsTheme = "light";
     }
     document.documentElement.setAttribute("devtoolstheme", devtoolsTheme);
-    this._updateLWTBrightness();
     this._inferBrightness();
   },
 
   handleEvent(e) {
     if (e.type === "load") {
       this.styleSheet.removeEventListener("load", this);
       this.refreshBrowserDisplay();
     }
@@ -120,17 +108,16 @@ var DevEdition = {
       this.styleSheet.sheet.disabled = true;
       this.refreshBrowserDisplay();
     }
   },
 
   uninit() {
     Services.prefs.removeObserver(this._devtoolsThemePrefName, this);
     Services.obs.removeObserver(this, "lightweight-theme-styling-update", false);
-    Services.obs.removeObserver(this, "lightweight-theme-window-updated", false);
     if (this.styleSheet) {
       this.styleSheet.removeEventListener("load", this);
     }
     this.styleSheet = null;
   }
 };
 
 // If the DevEdition theme is going to be applied in gBrowserInit.onLoad,