Bug 1309861 - enable SAB+Atomics by default on DevEd. r=jorendorff

--HG--
extra : rebase_source : 2c0897cec8b7d787ece516980b9ef880035e7781
extra : amend_source : 6b5526fcdc5a58d25a92b84a88c60181794b64cd

modules/libpref/init/all.js

@@ -1289,10 +1289,11 @@ pref("javascript.options.mem.gc_max_empty_chunk_count", 30);
 
 pref("javascript.options.showInConsole", false);
 
-#ifdef NIGHTLY_BUILD
-pref("javascript.options.shared_memory", true);
-#else
+#ifdef RELEASE_BUILD
+// Disabled in Beta and Release for now, see bug 1225406
 pref("javascript.options.shared_memory", false);
+#else
+pref("javascript.options.shared_memory", true);
 #endif
 
 pref("javascript.options.throw_on_debuggee_would_run", false);