--- a/toolkit/devtools/Loader.jsm
+++ b/toolkit/devtools/Loader.jsm
@@ -46,16 +46,17 @@ var BuiltinProvider = {
         "toolkit/loader": loader
       },
       paths: {
         "": "resource://gre/modules/commonjs/",
         "main": "resource:///modules/devtools/main.js",
         "devtools": "resource:///modules/devtools",
         "devtools/server": "resource://gre/modules/devtools/server",
         "devtools/toolkit/webconsole": "resource://gre/modules/devtools/toolkit/webconsole",
+        "devtools/styleinspector/css-logic": "resource://gre/modules/devtools/styleinspector/css-logic",
 
         // Allow access to xpcshell test items from the loader.
         "xpcshell-test": "resource://test"
       },
       globals: loaderGlobals
     });
 
     return promise.resolve(undefined);
@@ -80,26 +81,29 @@ var SrcdirProvider = {
     let srcdir = Services.prefs.getComplexValue("devtools.loader.srcdir",
                                                 Ci.nsISupportsString);
     srcdir = OS.Path.normalize(srcdir.data.trim());
     let devtoolsDir = OS.Path.join(srcdir, "browser", "devtools");
     let devtoolsURI = this.fileURI(devtoolsDir);
     let toolkitURI = this.fileURI(OS.Path.join(srcdir, "toolkit", "devtools"));
     let serverURI = this.fileURI(OS.Path.join(srcdir, "toolkit", "devtools", "server"));
     let webconsoleURI = this.fileURI(OS.Path.join(srcdir, "toolkit", "devtools", "webconsole"));
+    let cssLogicURI = this.fileURI(OS.Path.join(toolkitURI, "styleinspector", "css-logic"));
+
     let mainURI = this.fileURI(OS.Path.join(srcdir, "browser", "devtools", "main.js"));
     this.loader = new loader.Loader({
       modules: {
         "toolkit/loader": loader
       },
       paths: {
         "": "resource://gre/modules/commonjs/",
         "devtools/server": serverURI,
         "devtools/toolkit/webconsole": webconsoleURI,
         "devtools": devtoolsURI,
+        "devtools/styleinspector/css-logic": cssLogicURI,
         "main": mainURI
       },
       globals: loaderGlobals
     });
 
     return this._writeManifest(devtoolsDir).then(null, Cu.reportError);
   },
 

--- a/toolkit/devtools/moz.build
+++ b/toolkit/devtools/moz.build
@@ -5,10 +5,11 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 PARALLEL_DIRS += [
     'server',
     'client',
     'gcli',
     'sourcemap',
     'webconsole',
-    'apps'
+    'apps',
+    'styleinspector'
 ]

new file mode 100644
--- /dev/null
+++ b/toolkit/devtools/styleinspector/Makefile.in
@@ -0,0 +1,15 @@
+# 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/.
+
+DEPTH = ../../..
+topsrcdir = @top_srcdir@
+srcdir = @srcdir@
+VPATH = @srcdir@
+
+include $(DEPTH)/config/autoconf.mk
+
+include $(topsrcdir)/config/rules.mk
+
+libs::
+	$(INSTALL) $(IFLAGS1) $(srcdir)/*.js $(FINAL_TARGET)/modules/devtools/styleinspector

rename from browser/devtools/styleinspector/css-logic.js
rename to toolkit/devtools/styleinspector/css-logic.js

new file mode 100644
--- /dev/null
+++ b/toolkit/devtools/styleinspector/moz.build
@@ -0,0 +1,5 @@
+# -*- Mode: python; c-basic-offset: 4; 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/.