Bug 1538594 - Fix disabling the nursery r=jonco

Differential Revision: https://phabricator.services.mozilla.com/D25715

--HG--
extra : moz-landing-system : lando

js/src/gc/Nursery.cpp

@@ -860,12 +860,6 @@ void js::Nursery::collect(JS::GCReason reason) {
   if (rt->gc.heapSize.gcBytes() >= tunables().gcMaxBytes()) {
     disable();
   }
-  // Disable the nursery if the user changed the configuration setting.  The
-  // nursery can only be re-enabled by resetting the configurationa and
-  // restarting firefox.
-  if (chunkCountLimit_ == 0) {
-    disable();
-  }
 
   endProfile(ProfileKey::Total);
   rt->gc.incMinorGcNumber();
@@ -1219,6 +1213,14 @@ void js::Nursery::maybeResizeNursery(JS::GCReason reason) {
 }
 
 bool js::Nursery::maybeResizeExact(JS::GCReason reason) {
+  // Disable the nursery if the user changed the configuration setting. The
+  // nursery can only be re-enabled by resetting the configuration and
+  // restarting firefox.
+  if (tunables().gcMaxNurseryBytes() == 0) {
+    disable();
+    return true;
+  }
+
   // Shrink the nursery to its minimum size of we ran out of memory or
   // received a memory pressure event.
   if (gc::IsOOMReason(reason)) {

js/src/jit-test/tests/gc/bug1538594.js

@@ -0,0 +1,9 @@
+
+// This disables the nursery.
+gcparam('maxNurseryBytes', 0);
+
+assertEq(gcparam('maxNurseryBytes'), 0);
+gc();
+
+
+