Bug 1435458 - Preprocess the official firefox-branding.js. r=glandium

MozReview-Commit-ID: 6tVd9Xcyija

--HG--
extra : rebase_source : 9f2d74d823a24661ba69a0ae0b59fe5e167a1d61

browser/branding/branding-common.mozbuild

@@ -6,7 +6,7 @@
 
 @template
 def FirefoxBranding():
-    JS_PREFERENCE_FILES += [
+    JS_PREFERENCE_PP_FILES += [
         'pref/firefox-branding.js',
     ]