Only restart the GPU process multiple times on Nightly. (bug 1369097, r=milan)

modules/libpref/init/all.js

@@ -4685,10 +4685,10 @@ pref("layers.bench.enabled", false);
 
 #if defined(XP_WIN)
 pref("layers.gpu-process.enabled", true);
-pref("layers.gpu-process.max_restarts", 3);
 pref("media.gpu-process-decoder", true);
 #ifdef NIGHTLY_BUILD
 pref("layers.gpu-process.allow-software", true);
+pref("layers.gpu-process.max_restarts", 3);
 #endif
 #endif