--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -7403,17 +7403,16 @@ AutoAssertNoNurseryAlloc::AutoAssertNoNu
 }
 
 AutoAssertNoNurseryAlloc::~AutoAssertNoNurseryAlloc()
 {
     TlsContext.get()->allowNurseryAlloc();
 }
 
 JS::AutoEnterCycleCollection::AutoEnterCycleCollection(JSRuntime* rt)
-  : runtime(rt)
 {
     MOZ_ASSERT(!JS::CurrentThreadIsHeapBusy());
     TlsContext.get()->heapState = HeapState::CycleCollecting;
 }
 
 JS::AutoEnterCycleCollection::~AutoEnterCycleCollection()
 {
     MOZ_ASSERT(JS::CurrentThreadIsHeapCycleCollecting());

--- a/js/src/jspubtd.h
+++ b/js/src/jspubtd.h
@@ -196,18 +196,16 @@ CurrentThreadIsHeapCycleCollecting()
     return CurrentThreadHeapState() == HeapState::CycleCollecting;
 }
 
 // Decorates the Unlinking phase of CycleCollection so that accidental use
 // of barriered accessors results in assertions instead of leaks.
 class MOZ_STACK_CLASS JS_PUBLIC_API(AutoEnterCycleCollection)
 {
 #ifdef DEBUG
-    JSRuntime* runtime;
-
   public:
     explicit AutoEnterCycleCollection(JSRuntime* rt);
     ~AutoEnterCycleCollection();
 #else
   public:
     explicit AutoEnterCycleCollection(JSRuntime* rt) {}
     ~AutoEnterCycleCollection() {}
 #endif