Bug 1361258 - Backout 2214b3c57c9c (bug 1291356), disabling multiple jemalloc arenas. r=glandium

memory/mozjemalloc/jemalloc.c

@@ -143,14 +143,8 @@
  * Use only one arena by default.  Mozilla does not currently make extensive
  * use of concurrent allocation, so the increased fragmentation associated with
  * multiple arenas is not warranted.
- *
- * When using the Servo style system, we do indeed make use of significant
- * concurrent allocation, and the overhead matters. Bug 1291355 tracks
- * investigating the fragmentation overhead of turning this on for users.
  */
-#ifndef MOZ_STYLO
-#define MOZ_MEMORY_NARENAS_DEFAULT_ONE
-#endif
+#define	MOZ_MEMORY_NARENAS_DEFAULT_ONE
 
 /*
  * Pass this set of options to jemalloc as its default. It does not override