diff --git a/xpcom/base/CycleCollectedJSContext.cpp b/xpcom/base/CycleCollectedJSContext.cpp
index 220775d1a..12456b3bf 100644
--- a/xpcom/base/CycleCollectedJSContext.cpp
+++ b/xpcom/base/CycleCollectedJSContext.cpp
@@ -1421,6 +1421,8 @@ CycleCollectedJSContext::ProcessStableStateQueue()
   MOZ_RELEASE_ASSERT(!mDoingStableStates);
   mDoingStableStates = true;
 
+  // When run, one event can add another event to the mStableStateEvents, as
+  // such you can't use iterators here.
   for (uint32_t i = 0; i < mStableStateEvents.Length(); ++i) {
     nsCOMPtr<nsIRunnable> event = mStableStateEvents[i].forget();
     event->Run();
@@ -1508,7 +1510,7 @@ CycleCollectedJSContext::AfterProcessMicrotasks()
 }
 
 uint32_t
-CycleCollectedJSContext::RecursionDepth()
+CycleCollectedJSContext::RecursionDepth() const
 {
   return mOwningThread->RecursionDepth();
 }
diff --git a/xpcom/base/CycleCollectedJSContext.h b/xpcom/base/CycleCollectedJSContext.h
index 9faa16671..b312a689f 100644
--- a/xpcom/base/CycleCollectedJSContext.h
+++ b/xpcom/base/CycleCollectedJSContext.h
@@ -364,7 +364,7 @@ public:
   virtual void BeforeProcessTask(bool aMightBlock);
   virtual void AfterProcessTask(uint32_t aRecursionDepth);
 
-  uint32_t RecursionDepth();
+  uint32_t RecursionDepth() const;
 
   // Run in stable state (call through nsContentUtils)
   void RunInStableState(already_AddRefed<nsIRunnable>&& aRunnable);
@@ -404,12 +404,12 @@ public:
     }
   }
 
-  bool IsInMicroTask()
+  bool IsInMicroTask() const
   {
     return mMicroTaskLevel != 0;
   }
 
-  uint32_t MicroTaskLevel()
+  uint32_t MicroTaskLevel() const
   {
     return mMicroTaskLevel;
   }
@@ -423,7 +423,7 @@ public:
 
   void PerformDebuggerMicroTaskCheckpoint();
 
-  bool IsInStableOrMetaStableState()
+  bool IsInStableOrMetaStableState() const
   {
     return mDoingStableStates;
   }