Merge branch 'redwood' into releaseRELBASE_20200930

1 files changed, 6 insertions, 0 deletions

diff --git a/dom/base/ResizeObserverController.cpp b/dom/base/ResizeObserverController.cpp
index 924bba10d1..349cb66baf 100644
--- a/dom/base/ResizeObserverController.cpp
+++ b/dom/base/ResizeObserverController.cpp
@@ -59,6 +59,12 @@ ResizeObserverNotificationHelper::Register()
 void
 ResizeObserverNotificationHelper::Unregister()
 {
+  if (!mOwner) {
+    // We've outlived our owner, so there's nothing registered anymore.
+    mRegistered = false;
+    return;
+  }
+
   if (!mRegistered) {
     return;
   }