Bug 1710879 - Don't clear BrowserBridgeHost::mBridge until BrowserBridgeChild has been completely destroyed. r=nika

Differential Revision: https://phabricator.services.mozilla.com/D122214

dom/ipc/BrowserBridgeChild.cpp

@@ -214,6 +214,10 @@ mozilla::ipc::IPCResult BrowserBridgeChild::RecvSubFrameCrashed() {
 }
 
 void BrowserBridgeChild::ActorDestroy(ActorDestroyReason aWhy) {
+  if (mFrameLoader) {
+    mFrameLoader->DestroyComplete();
+  }
+
   if (!mBrowsingContext) {
     // This BBC was never valid, skip teardown.
     return;