--- a/Makefile.in
+++ b/Makefile.in
@@ -42,17 +42,17 @@ endif
 
 BUILD_BACKEND_FILES := $(addprefix backend.,$(addsuffix Backend,$(BUILD_BACKENDS)))
 
 ifndef TEST_MOZBUILD
 ifndef MOZ_PROFILE_USE
 # We need to explicitly put BUILD_BACKEND_FILES here otherwise the rule in
 # rules.mk doesn't run early enough.
 $(TIERS) binaries:: CLOBBER $(configure_dir)/configure config.status $(BUILD_BACKEND_FILES)
-ifndef JS_STANDALONE
+ifdef MOZ_WIDGET_TOOLKIT
 ifdef COMPILE_ENVIRONMENT
 $(TIERS) binaries:: $(topsrcdir)/js/src/configure js/src/config.status
 endif
 endif
 endif
 endif
 
 ifdef JS_STANDALONE
@@ -117,17 +117,17 @@ install_manifests += dist/bin
 endif
 install_manifest_depends = \
   CLOBBER \
   $(configure_dir)/configure \
   config.status \
   $(BUILD_BACKEND_FILES) \
   $(NULL)
 
-ifndef JS_STANDALONE
+ifdef MOZ_WIDGET_TOOLKIT
 ifdef COMPILE_ENVIRONMENT
 install_manifest_depends += \
   $(topsrcdir)/js/src/configure \
   js/src/config.status \
   $(NULL)
 endif
 endif
 
@@ -208,17 +208,17 @@ else # !MOZ_PROFILE_USE (normal build)
 recurse_pre-export:: install-manifests
 binaries::
 	@$(MAKE) install-manifests install_manifests=dist/include
 endif
 
 recurse_artifact:
 	$(topsrcdir)/mach --log-no-times artifact install
 
-ifndef JS_STANDALONE
+ifdef MOZ_WIDGET_TOOLKIT
 ifdef ENABLE_TESTS
 # Additional makefile targets to call automated test suites
 include $(topsrcdir)/testing/testsuite-targets.mk
 endif
 endif
 
 default all::
 	$(call BUILDSTATUS,TIERS $(TIERS) $(if $(MOZ_AUTOMATION),$(MOZ_AUTOMATION_TIERS)))

--- a/build/gecko_templates.mozbuild
+++ b/build/gecko_templates.mozbuild
@@ -62,17 +62,17 @@ def GeckoBinary(linkage='dependent', msv
                 LDFLAGS += ['-rdynamic']
         elif mozglue == 'library':
             LIBRARY_DEFINES['MOZ_HAS_MOZGLUE'] = True
             if not CONFIG['MOZ_GLUE_IN_PROGRAM']:
                 USE_LIBS += ['mozglue']
         else:
             error('`mozglue` must be "program" or "library"')
 
-    if not CONFIG['JS_STANDALONE']:
+    if CONFIG['MOZ_WIDGET_TOOLKIT']:
         USE_LIBS += [
             'fallible',
         ]
 
 
 @template
 def GeckoProgram(name, linkage='standalone', **kwargs):
     '''Template for program executables related to Gecko.

--- a/memory/moz.build
+++ b/memory/moz.build
@@ -8,16 +8,16 @@ with Files("**"):
     BUG_COMPONENT = ("Core", "Memory Allocator")
 
 DIRS += [
     'build',
     'mozalloc',
     'fallible',
 ]
 
-if not CONFIG['JS_STANDALONE']:
+if CONFIG['MOZ_WIDGET_TOOLKIT']:
     DIRS += ['volatile']
 
 # NB: gtest dir is included in toolkit/toolkit.build due to its dependency
 # on libxul.
 
 if CONFIG['MOZ_REPLACE_MALLOC']:
     DIRS += ['replace']

--- a/mfbt/tests/moz.build
+++ b/mfbt/tests/moz.build
@@ -1,15 +1,15 @@
 # -*- 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/.
 
-if not CONFIG['JS_STANDALONE']:
+if CONFIG['MOZ_WIDGET_TOOLKIT']:
     TEST_DIRS += [
         'gtest',
     ]
 
 CppUnitTests([
     'TestArray',
     'TestArrayUtils',
     'TestAtomics',

--- a/moz.build
+++ b/moz.build
@@ -62,17 +62,17 @@ if CONFIG['ENABLE_CLANG_PLUGIN']:
 DIRS += [
     'config',
     'python',
     'taskcluster',
     'testing/mozbase',
     'third_party/python',
 ]
 
-if not CONFIG['JS_STANDALONE']:
+if CONFIG['MOZ_WIDGET_TOOLKIT']:
     # These python manifests are included here so they get picked up without an objdir
     PYTHON_UNITTEST_MANIFESTS += [
         'layout/tools/reftest/selftest/python.ini',
         'testing/marionette/harness/marionette_harness/tests/harness_unit/python.ini',
         'testing/mochitest/tests/python/python.ini',
     ]
 
     CONFIGURE_SUBST_FILES += [
@@ -109,24 +109,24 @@ DIRS += [
     'config/external/fdlibm',
     'config/external/nspr',
     'config/external/zlib',
     'memory',
     'mfbt',
     'mozglue',
 ]
 
-if not CONFIG['JS_STANDALONE']:
+if CONFIG['MOZ_WIDGET_TOOLKIT']:
     DIRS += ['xpcom/xpidl']
 
 if CONFIG['USE_ICU']:
     DIRS += ['config/external/icu']
 
 if CONFIG['COMPILE_ENVIRONMENT']:
-    if not CONFIG['JS_STANDALONE']:
+    if CONFIG['MOZ_WIDGET_TOOLKIT']:
         DIRS += [
             'config/external',
             'security',
         ]
 
     if CONFIG['BUILD_CTYPES']:
         DIRS += ['config/external/ffi']
 

--- a/mozglue/build/moz.build
+++ b/mozglue/build/moz.build
@@ -23,17 +23,17 @@ if CONFIG['MOZ_ASAN']:
 
 if CONFIG['OS_TARGET'] == 'WINNT':
     DEFFILE = 'mozglue.def'
     # We'll break the DLL blocklist if we immediately load user32.dll
     DELAYLOAD_DLLS += [
         'user32.dll',
     ]
 
-if not CONFIG['JS_STANDALONE']:
+if CONFIG['MOZ_WIDGET_TOOLKIT']:
 
     if CONFIG['MOZ_MEMORY'] and FORCE_SHARED_LIB:
         pass
         # TODO: SHARED_LIBRARY_LIBS go here
     else:
         # Temporary, until bug 662814 lands
         NoVisibilityFlags()
         SOURCES += [

--- a/mozglue/moz.build
+++ b/mozglue/moz.build
@@ -13,10 +13,10 @@ if CONFIG['MOZ_LINKER']:
 if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'android':
     DIRS += ['android']
 
 DIRS += [
   'build',
   'misc',
 ]
 
-if not CONFIG['JS_STANDALONE']:
+if CONFIG['MOZ_WIDGET_TOOLKIT']:
     TEST_DIRS += ['tests']