Bug 1374492 - Don't let extensions disable e10s in DevEdition. r=Felipe

MozReview-Commit-ID: DBRl8Sx8QQ3

--HG--
extra : rebase_source : e5de738c5f552b3775f26e7e8a707143e216ae4c

browser/app/profile/firefox.js

@@ -1561,7 +1561,7 @@ pref("extensions.allow-non-mpc-extensions", false);
 #endif
 
 // Enable blocking of e10s and e10s-multi for add-on users on beta/release.
-#ifdef RELEASE_OR_BETA
+#if defined(RELEASE_OR_BETA) && !defined(MOZ_DEV_EDITION)
 pref("extensions.e10sBlocksEnabling", true);
 pref("extensions.e10sMultiBlocksEnabling", true);
 #endif