--- a/layout/base/nsRefreshDriver.cpp
+++ b/layout/base/nsRefreshDriver.cpp
@@ -1861,17 +1861,18 @@ nsRefreshDriver::Tick(int64_t aNowEpoch,
   }
 
   // Resize events should be fired before layout flushes or
   // calling animation frame callbacks.
   AutoTArray<nsIPresShell*, 16> observers;
   observers.AppendElements(mResizeEventFlushObservers);
   for (uint32_t i = observers.Length(); i; --i) {
     if (!mPresContext || !mPresContext->GetPresShell()) {
-      break;
+      StopTimer();
+      return;
     }
     // Make sure to not process observers which might have been removed
     // during previous iterations.
     nsIPresShell* shell = observers[i - 1];
     if (!mResizeEventFlushObservers.Contains(shell)) {
       continue;
     }
     mResizeEventFlushObservers.RemoveElement(shell);